Threat database

Improper Authentication vulnerability in Apache Camel Keycloak component. This issue affects Apache Camel: from 4.15.0 before 4.18.5, from 4.19.0 before 4.22.1. The security processor validated the issuer of an introspected token only when the introspection response actually carried an iss claim. When the claim was absent the check was skipped rather than treated as a failure, so a token that the configured issuer did not mint could be accepted provided the introspection endpoint answered without naming an issuer. Reaching this requires an introspection endpoint that omits iss and accepts tokens from more than one issuer, which is not the default Keycloak arrangement, hence the low severity; where that arrangement exists the consequence is that the deployment authenticates a caller it should have rejected. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. An absent iss claim is now treated as a validation failure rather than as a reason to skip the check. For deployments that cannot upgrade immediately, ensure the introspection endpoint returns the iss claim, and that it serves exactly one issuer.

Exposure of Data Element to Wrong Session vulnerability in Apache Camel AS2 component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. Signing material belonging to an individual request was stored in state that is shared across requests rather than confined to the request being processed. Where a deployment serves more than one trading partner, concurrent or successive requests could therefore observe each other's material, and a Message Disposition Notification could be signed with the key of a partner other than the one the receipt was for. The result is cross-partner key confusion: a receipt attributable to the wrong partner, and one partner's signing material used while handling another partner's exchange. AS2 deployments are typically multi-partner by design, so the condition is reached by ordinary concurrent traffic rather than by anything the attacker must arrange. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. Per-request signing keys are now confined to the request being processed in ResponseMDN. For deployments that cannot upgrade immediately, run a separate Camel context per trading partner so that no signing material is shared between them.

Insertion of Sensitive Information into Log File vulnerability in Apache Camel MLLP component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. The camel-mllp component carries a logPhi option that governs whether HL7 payload content may be written to the log. It defaulted to true, so a deployment that did nothing logged protected health information out of the box. Two further paths wrote payload content to the log regardless of the setting, so even an operator who had turned logPhi off was still exposed on those paths. MLLP is used to carry HL7 clinical messages, so the content concerned is patient data, and it reached ordinary application logs where it is subject to whatever retention, aggregation and access the deployment applies to logs generally rather than to clinical records. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. logPhi now defaults to false and is honoured on the paths that previously ignored it. This is a changed default: a deployment that relied on payload logging must now set logPhi=true explicitly. Because the upgrade guide for a change like this lives on the main branch only, operators upgrading within the 4.18.x or 4.22.x lines should treat this advisory as the notice of that change. For deployments that cannot upgrade immediately, set logPhi=false and be aware that two paths will continue to log payload content until the fix is applied; restrict access to the logs accordingly.

Generation of Error Message Containing Sensitive Information vulnerability in Apache Camel CXF component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. When a route behind a CXF SOAP consumer failed with an exception the service contract does not declare, the exception was described back to the SOAP client in the fault: CXF copies the message into the SOAP faultstring, and can be configured to place the stack trace in the fault detail. An external caller able to provoke a failure could therefore read internal detail about the deployment - class and package names, and whatever the exception message carries. Declared faults, annotated @WebFault, are a different matter: those are part of the published contract that clients are written against, and suppressing them would break the service rather than protect anything. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. A muteException consumer option, defaulting to true, replaces an undeclared route failure with a generic fault carrying no class name, message or stack trace. Faults the contract declares are reported exactly as before. Set muteException=false to restore the previous output. For deployments that cannot upgrade immediately, declare the exceptions the service is allowed to report and map every other failure onto one of them in an onException handler, so no undeclared exception reaches the fault.

Improper Handling of Case Sensitivity vulnerability in Apache Camel Platform HTTP component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. The guard that prevents a request header being reflected into the response compared header names case sensitively, while HTTP header names are case insensitive. A caller could therefore defeat the suppression simply by varying the case of the header name. HTTP/2 makes the problem unconditional rather than optional: the protocol requires header names to be lowercase on the wire, so the comparison never matched and the suppression was inert for every request on an HTTP/2 connection. The consequence is that content the caller chose is echoed back in the response, which is the basis for response-splitting and cache-poisoning style attacks against whatever sits in front of the Camel endpoint. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. Request header names are now compared case insensitively, so the suppression holds regardless of casing and works under HTTP/2. For deployments that cannot upgrade immediately, strip the headers in question in front of the Camel endpoint, or remove them from the response in the route rather than relying on the built-in suppression.

Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection') vulnerability in Apache Johnzon. ClassConverter loads & static-initializes an attacker-named class from untrusted JSON. This issue affects Apache Johnzon: from 1.0.0 before 2.2.0. Users are recommended to upgrade to version 1.3.1 (javax namespace) or 2.2.0 (jakarta specification namespace), which fixes the issue.

Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Apache Camel HTTP component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. Two paths handed credentials to a redirect target, which is a host chosen by the remote server rather than by the route, once followRedirects=true. OAuth2ClientConfigurer registers its interceptor with addRequestInterceptorFirst, and HttpClient runs protocol-level request interceptors inside ProtocolExec, which sits below RedirectExec in the exec chain; the interceptor therefore ran again for every redirect hop and re-attached Authorization: Bearer to whatever host the Location header named. Separately, credentials were registered against an AuthScope matching any host, so basic and digest credentials were presented to a redirect target as well. A remote endpoint - or anyone who can influence its responses - could therefore collect the bearer token or the configured credentials simply by answering with a redirect to a host it controls. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. Credentials are now sent only to the authority the endpoint was configured with, and are not re-attached when a redirect crosses to another host. For deployments that cannot upgrade immediately, set followRedirects=false on endpoints that carry credentials, and handle any redirect explicitly in the route so that the destination is chosen by the route rather than by the remote server.

Improper Restriction of XML External Entity Reference vulnerability in Apache Camel XPath component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. With documentType set to InputSource, XPathBuilder handed the payload straight to javax.xml.xpath, which builds a DocumentBuilder of its own using the JDK defaults. The hardening applied to Camel's default document type was therefore bypassed: a DOCTYPE declaration that is refused on the default type was accepted here, and the external entity it declared was resolved and expanded into the evaluated document. An external sender whose XML reaches such an expression could read files readable by the Camel process and cause the process to issue requests to hosts it names. The two document types disagreeing on parser configuration is what made this reachable, since a deployment choosing InputSource for streaming reasons had no indication it was also choosing a weaker parser. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. The InputSource document type now goes through the same hardened parser as the default type, so a DOCTYPE is refused. Note that it also shares that type's documented escape hatch: the same DocumentBuilderFactory system properties that relax the default type relax this one, so a deployment that has set them remains unprotected by design. For deployments that cannot upgrade immediately, do not use documentType=InputSource on expressions evaluated over untrusted XML; the default document type already refuses a DOCTYPE.

Improper Input Validation vulnerability in Apache Camel Tika component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. The Tika producer mapped every metadata key parsed out of the submitted document onto the Exchange as a header, with no filter applied. Document metadata is attacker-controlled content: the party that supplies the file chooses the metadata keys it carries. A crafted document could therefore set Exchange headers that the rest of the route depends on, including headers in the Camel namespace such as CamelFileName, which downstream components use to decide where content is written. The pattern is the same header-injection class as the consumer advisories published previously, reached here through parsed file content rather than through a protocol header. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. Parsed document metadata is now filtered through a HeaderFilterStrategy before it is mapped onto the Exchange. A route that was reading a metadata-derived header the filter now blocks will see it missing. For deployments that cannot upgrade immediately, strip the Camel namespace after the Tika producer with removeHeaders("Camel*") before any component that acts on those headers.

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in Apache Camel PQC component. This issue affects Apache Camel: from 4.12.0 before 4.18.5, from 4.19.0 before 4.22.1. The producer held a single java.security.Signature instance and used it for every exchange without synchronizing access. Signature is stateful and is not thread safe: update() accumulates the data to be signed or verified, and verify() consumes that accumulated state. With concurrent exchanges sharing one instance the update and verify calls of different messages interleave, so a verification can complete against data that belongs to another exchange, or against a partially accumulated buffer. The outcome is non-deterministic and includes a verification reporting success for a message whose signature was never actually checked, which defeats the guarantee the component exists to provide. Reaching it requires concurrent traffic through the same endpoint, which is the ordinary condition for a Camel route under load. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. The Signature instance is no longer shared across concurrent exchanges. For deployments that cannot upgrade immediately, restrict the affected route to a single concurrent consumer so that no two exchanges use the instance at once.

Improper Certificate Validation vulnerability in Apache Camel Knative component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. When SSL was enabled on the Knative HTTP client but no truststore was configured, the client options fell back to trusting every presented certificate rather than to the JVM's default trust anchors. A deployment that switched TLS on without also configuring a truststore therefore obtained an encrypted connection with no peer authentication, which an attacker positioned on the network path can terminate and read. The dangerous state is reached by omission rather than by an explicit opt-in, which is what makes it a framework defect: turning TLS on should not be the thing that turns certificate validation off. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. With no truststore configured the trust options are now left unset so the JVM default trust anchors apply, the same fallback SSLContextParameters and the rest of Camel use. Trusting every certificate is now reached only by asking for it explicitly through the trust.all property, which remains available for development against a cluster with a self-signed certificate. For deployments that cannot upgrade immediately, configure a truststore explicitly wherever SSL is enabled. After upgrading, a deployment that was relying on the implicit trust-all behaviour must either configure a truststore or set the trust.all property deliberately.

Generation of Error Message Containing Sensitive Information vulnerability in Apache Camel Mina component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. When processing of an exchange failed, the Mina consumer wrote exchange.getException() straight back over the socket to the remote peer. Over a textline codec that hands the peer the exception's class name and message; over the object codec it hands over the serialised exception, cause chain included. A remote peer able to provoke a failure could therefore read internal detail about the deployment - class and package names, and whatever a message or nested cause happens to carry, which in practice can include paths, host names and connection detail. The consumer had no option to suppress this, unlike the HTTP-family consumers aligned by CAMEL-23651. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. A muteException consumer option, defaulting to true, replaces the route exception with a generic one carrying no class name, message or stack trace, while still writing a reply so that a synchronous peer is not left to time out. Set muteException=false to restore the previous behaviour. For deployments that cannot upgrade immediately, add an onException handler that sets the reply body explicitly, so the framework never writes the exception back to the peer.

Exposure of Data Element to Wrong Session vulnerability in Apache Camel Thrift component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. The Thrift data format unmarshalled incoming data into the shared defaultInstance of the target type rather than into a fresh copy, and returned that shared object as the exchange body. Because the instance is shared process-wide, state written while unmarshalling one message stayed on the object and was visible to every later message that used the same type. Fields absent from a later payload retained the previous message's values, so content belonging to one sender could be read while processing another sender's message, and concurrent exchanges could observe each other's partially written state. In a deployment that serves more than one tenant or user through the same route, that is disclosure of one party's data to another. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. Unmarshalling now deserializes into a copy, so each exchange gets its own instance and no state carries between messages. For deployments that cannot upgrade immediately, copy the unmarshalled body into a new instance immediately after the data format runs, and do not retain references to the returned object.

Improper Validation of Integrity Check Value vulnerability in Apache Camel Crypto PGP component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. unmarshal() verified the modification detection code only when the message was an OpenPGP symmetrically encrypted integrity protected data packet. The older symmetrically encrypted data packet carries no such code, and OpenPGP's CFB mode is malleable without one, so a message using that packet skipped the check altogether. The packet type is chosen by whoever produced the message, which left the sender - or anyone able to rewrite the message in transit - deciding whether the integrity check applied at all. The existing integrity option governs marshalling only and had no decrypt-side counterpart, so a deployment could not require integrity protection on the messages it accepted. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. A requireIntegrityProtection option, defaulting to true, now rejects a message that is not integrity protected. Note that signatureVerificationOption still defaults to optional, so a message carrying no signature is accepted; the two options together are what give a decrypted message authenticity and not only confidentiality. For deployments that cannot upgrade immediately, reject messages that do not use the integrity protected packet before they reach the data format. Routes that must interoperate with a sender still emitting the legacy packet should set requireIntegrityProtection=false after upgrading, and treat the decrypted content as unauthenticated.

Improper Authentication vulnerability in Apache Camel Shiro component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. The Shiro security processor skipped credential verification when the subject already bound to the current thread carried the same principal as the incoming exchange. Because the thread that carries a Camel exchange is drawn from a pool and reused across exchanges, a subject left bound by an earlier authenticated exchange could satisfy the check for a later one that presented no valid credentials of its own. The password on the incoming exchange was, in that case, never verified. The condition depends on thread reuse and on the principal matching, which is why it is not reached on every request, but it requires nothing of the attacker beyond sending a request naming a principal that is in active use. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. The processor now verifies the presented credentials on every exchange rather than accepting a subject already bound to the thread. Setting alwaysReauthenticate=false restores the previous behaviour for deployments that depend on it. For deployments that cannot upgrade immediately, ensure the Shiro subject is cleared from the thread at the end of every exchange so that no subject can be inherited by a later one.

Generation of Error Message Containing Sensitive Information vulnerability in Apache Camel Knative component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. When processing of an exchange failed on the consumer side, the Knative HTTP consumer wrote the resulting exception back to the remote caller as the response body, including its class name, message and stack trace. An external sender could therefore provoke a failure and read internal detail about the deployment: class and package names, file system or host names carried in exception messages, and the shape of the route. That detail is useful for building a more targeted attack, and where an exception message embeds configuration or connection strings it is disclosure in its own right. camel-knative was the remaining HTTP-family consumer that had not been aligned with the muteException behaviour established for the other HTTP consumers by CAMEL-23651. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. The consumer now honours a muteException option that defaults to true, so a route failure returns an empty body with the error status rather than the exception. Set muteException=false to restore the previous output. For deployments that cannot upgrade immediately, add an onException handler that sets the response body explicitly, so that the framework never writes the exception back to the caller.

Cross-Site Request Forgery (CSRF) vulnerability in Apache Camel OAuth component. This issue affects Apache Camel: from 4.11.0 before 4.18.5, from 4.19.0 before 4.22.1. The authorization code callback did not carry a state parameter binding it to the authorization request that started the flow, and the callback did not verify one. An authorization code obtained in any browser could therefore be redeemed at the callback and associated with whichever session presented it, which is login cross-site request forgery: a victim can be silently signed in as an identity the attacker controls, so that actions the victim then performs, and data they then submit, land in the attacker's account. The same unvalidated callback handling also allowed the post-authentication redirect target to be influenced, giving an open redirect from a trusted origin. The state check runs before the authorization code is redeemed, so these paths are reachable without any interaction with the identity provider. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. The authorization request now issues a state value bound to the session, and the callback rejects a request whose state is absent or does not match, stopping the route with a 400 response. For deployments that cannot upgrade immediately, terminate the authorization code flow in a component that performs its own state binding rather than relying on the Camel callback. Note that after upgrading, a deployment behind a proxy that drops or rewrites the callback query string will begin to see 400 responses, because the state parameter must survive the round trip.

Permissive Cross-domain Policy with Untrusted Domains vulnerability in Apache Camel Platform HTTP Vertx component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. createCorsHandler() set Access-Control-Allow-Credentials: true outside the origin check, so the header went out on every response to a request carrying an Origin header, including responses to origins the handler had just decided not to allow. When camel.server.cors.origins is unset, the handler treats every origin as allowed and echoes the caller's own Origin back as Access-Control-Allow-Origin. Together those produce the credentialed any-origin configuration that the fetch specification refuses to express as a literal wildcard, which is precisely why reflecting the origin is the usual way around that rule. A page on any origin could therefore make credentialed cross-origin requests to the Camel endpoint and read the responses. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. Access-Control-Allow-Credentials is now sent only when the request origin matched an origin the operator actually configured. With no origin list the origin is still reflected, as before, but credentials are not granted, and Vary: Origin is now set whenever the origin is reflected so that a shared cache cannot serve one origin's response to another. For deployments that cannot upgrade immediately, set camel.server.cors.origins to the explicit list of origins that need access rather than leaving it unset.

Improper Control of Generation of Code ('Code Injection'), Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection') vulnerability in Apache Camel. This issue affects Apache Camel: from 4.4.0 before 4.18.5, from 4.19.0 before 4.22.1. The dynamic-router-control endpoint, introduced in 4.4.0, lets routing participants manage Dynamic Router subscriptions by sending control messages. When it handled a subscribe or update request, DynamicRouterControlProducer took the subscription predicate and the name of the language used to compile it from the incoming message, either from the predicate and expressionLanguage fields of a DynamicRouterControlMessage body or from the CamelDynamicRouterPredicate and CamelDynamicRouterExpressionLanguage headers. DynamicRouterControlService then resolved that language from the CamelContext and compiled the expression into a Predicate, with no allow-list and no opt-in. The compiled predicate was added to the channel's rule base and evaluated against every exchange routed through the corresponding dynamic-router endpoint for as long as the subscription existed. A route that forwards messages from an external transport to the control endpoint, as shown in the component documentation for routing participants in other JVMs or applications, therefore let any actor able to send a message on that transport supply an expression of their choosing, which was evaluated with the privileges of the Camel process. Any expression language available on the classpath could be selected, including the simple language, which is always present and was the default on the header path, so removing optional expression languages from the classpath did not prevent the issue. Exploitation requires the ability to send a message on a transport whose route forwards it to a dynamic-router-control endpoint; no other authentication or user interaction is needed. Releases before 4.4.0 are not affected, because their control channel took predicate expressions only from the endpoint URI configured by the route author. Users are recommended to upgrade to version 4.23.0, which fixes the issue. If users are on the 4.22.x releases stream, then they are suggested to upgrade to 4.22.1. If users are on the 4.18.x releases stream, then they are suggested to upgrade to 4.18.5. The 4.14.x releases stream and earlier reached end of life before this issue was resolved and will not receive a fix, so deployments on those lines must move to a supported release. After upgrading, a control message that carries a predicate expression or an expression language is rejected unless the new allowPredicateFromMessage option is enabled on the dynamic-router-control endpoint; enable it only when every sender of control messages is trusted. For deployments that cannot upgrade immediately, do not forward messages from untrusted or shared transports to a dynamic-router-control endpoint. Where control messages must cross such a transport, authenticate the sender and make sure the predicate and expression language of each subscription are set by the route rather than taken from the incoming message, for example by removing the CamelDynamicRouterPredicate and CamelDynamicRouterExpressionLanguage headers and clearing the predicate and expressionLanguage fields of a DynamicRouterControlMessage before it reaches the endpoint. Removing optional expression languages from the classpath is not a sufficient workaround. As defence in depth, restrict who can send to the transports that feed the control endpoint, and on 4.23.0 and 4.22.1 set the allowedSchemes option of the dynamic-router endpoint to limit which endpoints a subscription's destinationUri may name.

Server-Side Request Forgery (SSRF) vulnerability in Apache Camel AS2 component. This issue affects Apache Camel: from 4.0.0 before 4.18.5, from 4.19.0 before 4.22.1. In the AS2 protocol the sender of a message may request that the Message Disposition Notification be returned asynchronously to an address the sender supplies. camel-as2 took that address from the inbound message and used it as the destination for the outgoing receipt without constraining it to anything the deployment had configured. A remote partner therefore chose the host the Camel instance would connect to when delivering the MDN. That gives server-side request forgery from the position of the AS2 receiver, including reaching hosts that are only routable from inside the deployment's network, and where the outbound connection carries credentials configured for MDN delivery those credentials are presented to the attacker-chosen destination. Upgrade to Apache Camel 4.23.0, which fixes the issue. Users on the 4.18.x LTS releases stream should upgrade to 4.18.5. Users on the 4.22.x LTS releases stream should upgrade to 4.22.1. The asynchronous MDN destination is now constrained rather than taken verbatim from the inbound message. For deployments that cannot upgrade immediately, restrict outbound connectivity from the AS2 receiver to the partner endpoints it legitimately delivers receipts to, and do not attach credentials to MDN delivery that are valid for any host other than those partners.