CVE-2026-56139: CWE-209 Generation of Error Message Containing Sensitive Information in Apache Software Foundation Apache Camel Undertow
Generation of Error Message Containing Sensitive Information vulnerability in Apache Camel Undertow Component. The camel-undertow HTTP server consumer exposes a muteException option that controls what is returned to the client when a route processing error occurs. This option defaulted to false, whereas the other Camel HTTP server components (camel-http / camel-jetty / camel-servlet and camel-platform-http) default it to true. With muteException=false, when a request triggers an exception during route processing the consumer writes the full Throwable stack trace into the HTTP response body as text/plain instead of returning an empty body. Any unauthenticated client that can reach the endpoint and cause a processing error - for example by sending a malformed request body, an invalid parameter, or otherwise triggering a route-internal failure - therefore receives a complete Java stack trace. Such a stack trace can disclose sensitive internal information, including credentials embedded in exception messages, internal host names and IP addresses, filesystem paths, dependency and version details, database and class names, and the application's internal structure, which an attacker can use to plan further attacks. In addition, for Rest DSL consumers the muteException option was not honoured at all: the RestUndertowHttpBinding was created with a hard-coded false, so the stack trace was returned even when muteException=true had been configured. This issue affects Apache Camel: from 4.0.0 before 4.14.8, from 4.15.0 before 4.18.3, from 4.19.0 before 4.21.0. Users are recommended to upgrade to version 4.21.0, which fixes the issue. If users are on the 4.14.x LTS releases stream, then they are suggested to upgrade to 4.14.8. If users are on the 4.18.x releases stream, then they are suggested to upgrade to 4.18.3. For deployments that cannot upgrade immediately, set muteException=true explicitly on the camel-undertow consumer (for example undertow: http://0.0.0.0:8080/api?muteException=true , or globally via the camel.component.undertow.mute-exception=true property), so that processing errors no longer return the stack trace to the client; note that on affected releases this workaround does not cover Rest DSL consumers, whose binding ignores the option until the fix is applied.
AI Analysis
Technical Summary
The Apache Camel Undertow HTTP server consumer exposes a vulnerability (CWE-209) where error messages include sensitive information due to the muteException option defaulting to false. When a route processing error occurs, the full Throwable stack trace is returned in the HTTP response body, exposing internal details such as credentials, hostnames, filesystem paths, and application structure. This behavior differs from other Camel HTTP components that default muteException to true. Additionally, Rest DSL consumers ignore the muteException setting and always return stack traces until fixed. The vulnerability affects Apache Camel Undertow versions from 4.0.0 before 4.14.8, 4.15.0 before 4.18.3, and 4.19.0 before 4.21.0. The issue is fixed in version 4.21.0 and in LTS releases 4.14.8 and 4.18.3. Users unable to upgrade immediately can mitigate by explicitly setting muteException=true, though this does not affect Rest DSL consumers on vulnerable versions.
Potential Impact
An unauthenticated attacker able to trigger route processing errors on the affected Apache Camel Undertow endpoints can receive detailed Java stack traces in HTTP responses. These stack traces may disclose sensitive internal information including credentials, internal hostnames and IP addresses, filesystem paths, dependency and version details, database and class names, and internal application structure. Such information disclosure can aid attackers in planning further attacks against the system.
Mitigation Recommendations
A fix is available in Apache Camel Undertow version 4.21.0, and in LTS releases 4.14.8 and 4.18.3. Users are strongly recommended to upgrade to these versions to resolve the issue. For deployments that cannot upgrade immediately, explicitly set the muteException option to true on the camel-undertow consumer (e.g., undertow:http://0.0.0.0:8080/api?muteException=true or globally via camel.component.undertow.mute-exception=true) to prevent stack traces from being returned on processing errors. Note that this workaround does not apply to Rest DSL consumers on affected versions, as they ignore the muteException setting until the fix is applied.
CVE-2026-56139: CWE-209 Generation of Error Message Containing Sensitive Information in Apache Software Foundation Apache Camel Undertow
Description
Generation of Error Message Containing Sensitive Information vulnerability in Apache Camel Undertow Component. The camel-undertow HTTP server consumer exposes a muteException option that controls what is returned to the client when a route processing error occurs. This option defaulted to false, whereas the other Camel HTTP server components (camel-http / camel-jetty / camel-servlet and camel-platform-http) default it to true. With muteException=false, when a request triggers an exception during route processing the consumer writes the full Throwable stack trace into the HTTP response body as text/plain instead of returning an empty body. Any unauthenticated client that can reach the endpoint and cause a processing error - for example by sending a malformed request body, an invalid parameter, or otherwise triggering a route-internal failure - therefore receives a complete Java stack trace. Such a stack trace can disclose sensitive internal information, including credentials embedded in exception messages, internal host names and IP addresses, filesystem paths, dependency and version details, database and class names, and the application's internal structure, which an attacker can use to plan further attacks. In addition, for Rest DSL consumers the muteException option was not honoured at all: the RestUndertowHttpBinding was created with a hard-coded false, so the stack trace was returned even when muteException=true had been configured. This issue affects Apache Camel: from 4.0.0 before 4.14.8, from 4.15.0 before 4.18.3, from 4.19.0 before 4.21.0. Users are recommended to upgrade to version 4.21.0, which fixes the issue. If users are on the 4.14.x LTS releases stream, then they are suggested to upgrade to 4.14.8. If users are on the 4.18.x releases stream, then they are suggested to upgrade to 4.18.3. For deployments that cannot upgrade immediately, set muteException=true explicitly on the camel-undertow consumer (for example undertow: http://0.0.0.0:8080/api?muteException=true , or globally via the camel.component.undertow.mute-exception=true property), so that processing errors no longer return the stack trace to the client; note that on affected releases this workaround does not cover Rest DSL consumers, whose binding ignores the option until the fix is applied.
Affected software
pkg:maven/Apache Software Foundation/org.apache.camel:camel-undertowRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Apache Camel Undertow HTTP server consumer exposes a vulnerability (CWE-209) where error messages include sensitive information due to the muteException option defaulting to false. When a route processing error occurs, the full Throwable stack trace is returned in the HTTP response body, exposing internal details such as credentials, hostnames, filesystem paths, and application structure. This behavior differs from other Camel HTTP components that default muteException to true. Additionally, Rest DSL consumers ignore the muteException setting and always return stack traces until fixed. The vulnerability affects Apache Camel Undertow versions from 4.0.0 before 4.14.8, 4.15.0 before 4.18.3, and 4.19.0 before 4.21.0. The issue is fixed in version 4.21.0 and in LTS releases 4.14.8 and 4.18.3. Users unable to upgrade immediately can mitigate by explicitly setting muteException=true, though this does not affect Rest DSL consumers on vulnerable versions.
Potential Impact
An unauthenticated attacker able to trigger route processing errors on the affected Apache Camel Undertow endpoints can receive detailed Java stack traces in HTTP responses. These stack traces may disclose sensitive internal information including credentials, internal hostnames and IP addresses, filesystem paths, dependency and version details, database and class names, and internal application structure. Such information disclosure can aid attackers in planning further attacks against the system.
Mitigation Recommendations
A fix is available in Apache Camel Undertow version 4.21.0, and in LTS releases 4.14.8 and 4.18.3. Users are strongly recommended to upgrade to these versions to resolve the issue. For deployments that cannot upgrade immediately, explicitly set the muteException option to true on the camel-undertow consumer (e.g., undertow:http://0.0.0.0:8080/api?muteException=true or globally via camel.component.undertow.mute-exception=true) to prevent stack traces from being returned on processing errors. Note that this workaround does not apply to Rest DSL consumers on affected versions, as they ignore the muteException setting until the fix is applied.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- apache
- Date Reserved
- 2026-06-19T09:53:55.822Z
- Cvss Version
- null
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4b6cb027e9c797192526a9
Added to database: 07/06/2026, 08:52:00 UTC
Last enriched: 07/06/2026, 09:06:42 UTC
Last updated: 07/06/2026, 10:47:59 UTC
Views: 6
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