CVE-2026-66835 is a path equivalence vulnerability in the Erlang/OTP inets httpd server that allows remote unauthenticated attackers to bypass mod_auth directory protections by using multiple leading slashes in the request path. This causes the authentication check to fail due to a mismatch in path normalization and regex matching, enabling unauthorized file reads within protected directories. The vulnerability affects multiple OTP and inets versions prior to specific fixed releases.
Missing Release of Resource after Effective Lifetime vulnerability in Erlang/OTP inets httpd allows an unauthenticated remote attacker to cause denial of service by sending a request with a chunked body whose chunk-size line is not a hexadecimal number. The worker serving the connection is never released and no timeout reclaims it, so repeating the request across connections occupies every available worker and denies service to legitimate clients. No authentication is required and the default configuration is affected.
The chunk-size line must arrive in a write separate from the headers. When the body accompanies the headers, httpd_request_handler:handle_body/3 calls http_chunk:decode/3 inside a try ... catch throw:Error, so the {error, {chunk_size, _}} thrown by http_chunk:decode_size/4 is answered with 400 Bad Request. When the chunk size arrives later, the decoder is resumed through a bare catch in httpd_request_handler:handle_info/2, which converts the throw into a return value rather than raising it; the resulting error tuple is then treated as the next decoder continuation, the socket is re-armed, and the worker waits for data that never comes. The request timeout has already been cancelled at the point the headers were accepted, and the periodic byte-rate check is only armed when minimum_bytes_per_second is configured, which it is not by default.
This issue affects OTP from OTP 18.1.4 before OTP 27.3.4.17, OTP 28.5.0.6, and OTP 29.0.6, corresponding to inets from 6.0.3 before 9.3.2.7, 9.6.2.3, and 9.7.2.
CVE-2026-70409 is a medium-severity vulnerability in Erlang/OTP's eldap module involving improper validation of the port component in LDAP referral URLs. A malicious or compromised LDAP server can supply a referral URL with an excessively long numeric port, causing the eldap:parse_port/2 function to perform costly arbitrary-precision integer conversions. This can degrade application availability by consuming significant processing time. The flaw affects multiple OTP versions from 17.0 up to but excluding patched versions 27.3.4.17, 28.5.0.6, and 29.0.6, as well as corresponding eldap library versions. Exploitation requires the application to pass server-supplied referrals to eldap:parse_ldap_url/1, which eldap itself does not call internally. No known exploits are reported in the wild.
CVE-2026-70405 is a medium severity vulnerability in Erlang/OTP's SNMP component caused by improper validation of the specified quantity in input. A remote attacker can send an SNMP message with a BER INTEGER whose length field is arbitrarily large, leading to excessive resource consumption during decoding. This can degrade system availability. The issue affects multiple OTP and SNMP versions prior to specific fixed releases.
CVE-2026-73270 is a high-severity vulnerability in Erlang/OTP's inets httpd module that improperly handles case sensitivity on case-insensitive filesystems. It allows remote unauthenticated attackers to bypass mod_auth directory protections by requesting files with different casing, leading to unauthorized file disclosure. This affects multiple OTP and inets versions prior to specific fixed releases. Case-sensitive filesystems are not affected.
CVE-2026-75538 is an integer overflow vulnerability in Erlang OTP's inet driver when using {packet,4} mode on an open TCP port. An attacker can trigger a signed overflow in packet length calculation, causing a buffer overflow that corrupts the BEAM VM allocator metadata and likely crashes the VM. Exploitation for remote code execution is considered extremely unlikely. This affects multiple OTP and erts versions prior to specific fixed releases.
CVE-2026-59696 is a medium severity vulnerability in Erlang/OTP's stdlib where improper validation of the port component in a URI allows a remote attacker to degrade service availability. The vulnerability arises because the function uri_string:get_port/1 converts a very long numeric port string to an integer without length bounds, causing excessive CPU consumption. This affects all applications parsing attacker-supplied URIs using uri_string:parse/1. The issue impacts OTP versions from 21.0 up to but not including 27.3.4.17, 28.0 up to 28.5.0.6, and 29.0 up to 29.0.6, as well as corresponding stdlib versions. No exploits are known in the wild, and no explicit patch links are provided in the data.
CVE-2026-71380 is a high-severity vulnerability in Erlang/OTP's inets httpd component that allows an unauthenticated remote attacker to cause a denial of service. The flaw arises from improper resource release after receiving partial HTTP request bodies with large Content-Length headers, leading to indefinite worker occupation. This affects multiple OTP and inets versions prior to specific fixed releases.
CVE-2026-71562 is a medium severity vulnerability in Erlang/OTP's inets httpc module involving improper validation of numeric header values. A malicious HTTP server can send a very long numeric header (e.g., Content-Length) that triggers expensive arbitrary-precision integer conversions, causing performance degradation. This affects multiple OTP and inets versions prior to specific patch releases.
CVE-2026-70399 is a denial-of-service vulnerability in Erlang/OTP inets httpd caused by allocation of resources without limits or throttling. An unauthenticated remote attacker can open and hold many simultaneous connections, exhausting server resources. The default max_clients limit of 150 is not applied if the option is not explicitly set, allowing unlimited connections. This affects multiple OTP and inets versions prior to specific fixed releases.
Improper Handling of Case Sensitivity vulnerability in Erlang Ecosystem Foundation oidcc_plug (Oidcc.Plug.Authorize module) renders the user agent session binding inert, removing a defense in depth control against replay of a stolen session.
This vulnerability is associated with program files lib/oidcc/plug/authorize.ex and lib/oidcc/plug/authorization_callback.ex, and program routines Oidcc.Plug.Authorize.call/2 and Oidcc.Plug.AuthorizationCallback.call/2.
Oidcc.Plug.Authorize.call/2 reads the initiating client's user agent with get_req_header(conn, "User-Agent"). Plug lowercases incoming header names, but get_req_header/2 matches the supplied key exactly and performs no normalization of its own, so the mixed-case lookup always returns an empty list and nil is written into the session. On the callback side, Oidcc.Plug.AuthorizationCallback treats a stored nil user agent as nothing to compare and returns :ok without inspecting the request. The two behaviours combine so that the check passes unconditionally on every request, including for deployments that explicitly opted in with check_useragent: true, and an authorization callback can be completed from a different user agent than the one that initiated the flow without detection. The check fails open silently, with no error and no log entry, so a deployment cannot tell the binding is absent.
The impact is limited to defense in depth. The inert check does not by itself allow an attacker to complete an authorization flow; it removes one layer that would otherwise hinder use of a stolen or leaked session, such as an exfiltrated session cookie replayed from a different client. The CSRF/state, nonce, and PKCE checks are unaffected and continue to function. Deployments that never enabled check_useragent are not affected in practice, since they never expected the binding. The corresponding lookup in Oidcc.Plug.AuthorizationCallback correctly uses the lowercase key and is not affected.
This issue affects oidcc_plug: from 0.1.0-alpha.3 before 0.5.0.
CVE-2026-66884 is a Cross-Site Request Forgery (CSRF) vulnerability in the Erlang Ecosystem Foundation's oidcc_plug library, specifically in the Oidcc.Plug.AuthorizationCallback module. The flaw allows an attacker to trick a victim's browser into completing an authorization flow that the victim did not initiate, potentially signing the victim into the attacker's account. This occurs because the callback endpoint processes requests without a valid session by disabling security checks, including nonce, state, PKCE, peer IP, and user agent validations. The vulnerability affects versions from 0.2.0-beta.1 before 0.5.0 of oidcc_plug.
The Erlang/OTP ssl application does not detect cycles when reconstructing an incomplete peer certificate chain during a TLS or DTLS handshake. In ssl_certificate:handle_incomplete_chain/5, the received chain is passed to ssl_certificate:build_certificate_chain/5, which walks issuer relationships via ssl_certificate:do_certificate_chain/7 with no cycle detection and no depth limit. When the peer supplies two mutually cross-signed certificates in unordered form (A issues B, B issues A), the issuer lookup alternates between the two certificates and the pair of functions recurses indefinitely, growing the call stack and chain accumulator without bound. An unauthenticated remote attacker can send a crafted certificate chain in a TLS or DTLS Certificate handshake message to exhaust available memory and crash the BEAM node. Only a TCP connection and a partial handshake are required; no authentication or completed handshake is needed, and both TLS/DTLS servers and clients are affected when processing peer certificate messages. This issue affects OTP from OTP 23.2 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15, corresponding to ssl from 10.2 before 11.7.4, 11.6.0.4 and 11.2.12.11.
The Erlang/OTP ssl TLS 1.2 (and earlier) and DTLS client does not verify that the cipher suite selected by the server in ServerHello was among the suites offered by the client in ClientHello. The client-side tls_handshake:hello/5 handler validates the negotiated protocol version and the downgrade sentinel but hands the server-chosen suite directly to ssl_handshake:handle_server_hello_extensions/9, which installs it without a membership check. The TLS 1.3 client path performs this check (per RFC 8446), so it is not affected.
An on-path attacker between the client and the intended server can respond with a ServerHello selecting an anonymous key exchange suite such as TLS_DH_anon_* or TLS_ECDH_anon_* that the client never offered. Anonymous suites do not require the server to present a certificate, so the entire verify_peer and cacerts configuration is bypassed: the attacker completes the handshake with its own ephemeral parameters, no certificate is validated, no hostname is checked, and ssl:connect returns {ok, Socket}. All subsequent application traffic is readable and modifiable by the attacker.
This issue affects OTP from OTP 17.0 before OTP 27.3.4.15, from OTP 28.0 before OTP 28.5.0.4, and from OTP 29.0 before OTP 29.0.4, corresponding to ssl from 5.3.4 before 11.2.12.11, from 11.3 before 11.6.0.4, and from 11.7 before 11.7.4. Whether OTP before OTP 17.0, corresponding to ssl before 5.3.4, is affected is unknown.
Signed to Unsigned Conversion Error and Out-of-bounds Write vulnerability in Erlang OTP erts allows an attacker who can supply a crafted Erlang external term format (ETF) binary to binary_to_term/1 to corrupt the BEAM heap pointer and crash the virtual machine. When decoding a LARGE_TUPLE_EXT term, the validation pass decoded_size() in erts/emulator/beam/external.c reads the 32-bit arity field as unsigned (get_uint32()), while the decode pass dec_term() reads the same field as a signed 32-bit integer (get_int32()) into an int. An arity wire value of 0x80000000 passes validation as 2147483648 but decodes as -2147483648, so the subsequent hp += n moves the heap allocation pointer backward. Neither pass enforces the runtime tuple-arity limit MAX_ARITYVAL. The result is an out-of-bounds heap write; in practice the VM detects an impossible heap size and aborts, denying service. The required padding is large when uncompressed but the compressed-ETF envelope shrinks it to a small payload on the wire. This issue affects OTP from OTP 25.0 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15, corresponding to erts from 13.0 before 17.0.4, 16.4.0.4 and 15.2.7.11.
Integer Underflow (Wrap or Wraparound) vulnerability in erlang otp erlang/otp (erts modules), erlang otp erts (erts modules) allows Forced Integer Overflow, Excessive Allocation. This vulnerability is associated with program files erts/emulator/beam/external.c, emulator/beam/external.c.
The BIT_BINARY_EXT tag (77) handler in the External Term Format (ETF) decoder accepts an encoding with both length and trailing-bits fields set to zero. The subsequent computation of the bitstring size underflows an unsigned integer, producing a value of roughly 2^64 that is then passed as a memory allocation size. The allocator aborts the entire node with a message such as "Cannot allocate 2305843009213693951 bytes of memory (of type binary)".
The crash is a VM-level abort, not an Erlang-level exception. It cannot be intercepted by supervision trees, by try/catch, or by passing the [safe] option to binary_to_term/2 (which only restricts atom creation and does not perform structural validation of binary encodings).
Any application that decodes ETF from untrusted sources via binary_to_term/1,2 or enif_binary_to_term() is exposed. The Erlang distribution protocol also decodes incoming terms through the same code path, but distribution is expected to run on trusted networks per the OTP Secure Coding Guidelines (DSG-011).
This issue affects OTP from OTP 27.0 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15, corresponding to erts from 15.0 before 17.0.4, 16.4.0.4 and 15.2.7.11.
Allocation of resources without limits in Erlang/OTP public_key certificate path validation allows a remote unauthenticated attacker to cause denial of service by sending a crafted X.509 certificate chain during the TLS handshake.
During RFC 5280 policy processing in public_key:pkix_path_validation/3, the certificate policy tree maintained by pubkey_policy_tree grows without an upper bound. When a certificate chain contains M policies per certificate and K certificates, the tree grows on the order of M^K nodes because pubkey_policy_tree:add_leaves/2 and pubkey_policy_tree:add_leaf_siblings/2 extend the tree per policy per certificate. A modest chain with many policies per certificate is enough to pin BEAM schedulers and exhaust the node's memory, taking down the entire VM. The attacker only needs to be able to present a certificate chain to the victim, which is the normal precondition for a TLS handshake, so exploitation succeeds against any incoming or outgoing TLS connection that validates the peer's chain (the default for SSL/TLS clients and mutual-TLS servers).
This is the same vulnerability class as OpenSSL's X509_verify_cert policy tree DoS.
This vulnerability is associated with program files lib/public_key/src/pubkey_policy_tree.erl and program routines pubkey_policy_tree:add_leaves/2 and pubkey_policy_tree:add_leaf_siblings/2.
This issue affects OTP from OTP 26.2 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15, corresponding to public_key from 1.15 before 1.21.4, 1.20.3.4 and 1.17.1.5.
Classic buffer overflow in the Erlang/OTP megaco flex scanner C driver allows a remote unauthenticated attacker to corrupt the driver's memory (and potentially achieve remote code execution or a denial-of-service crash) by sending a single text-encoded H.248/Megaco message containing an oversized property parm name.
When tokenizing a Local/Remote descriptor, mfs_load_property_groups extracts the attacker-controlled property name (bounded only by the message length) and, when no value follows, formats it into a fixed 512-byte error_msg field of the MfsErlDrvData struct using an unchecked sprintf call. Names longer than roughly 452 bytes overflow into the immediately following struct fields (text_buf, text_ptr, term_spec, term_spec_size, term_spec_index), overwriting live pointers and counters with attacker-chosen bytes. Subsequent scanner code writes and frees through the corrupted pointers, producing arbitrary write and arbitrary free primitives inside the BEAM VM process, which can be leveraged for remote code execution. On builds compiled with _FORTIFY_SOURCE the overflow is detected at runtime and terminates the process with SIGABRT, resulting in denial of service.
The overflow occurs in the flex scanner before any grammar or Megaco-level authentication processing, so exploitation requires only network reachability to the megaco transport port on a node configured with {scanner, flex}.
This vulnerability is associated with program files lib/megaco/src/flex/megaco_flex_scanner_drv.flex.src and program routines mfs_load_property_groups.
This issue affects OTP from OTP 17.0 before OTP 27.3.4.15, from OTP 28.0 before OTP 28.5.0.4, and from OTP 29.0 before OTP 29.0.4, corresponding to megaco from 3.17.1 before 4.7.2.2, from 4.8 before 4.8.3.1, and from 4.9 before 4.9.1. Whether OTP before OTP 17.0, corresponding to megaco before 3.17.1, is affected is unknown.
Relative Path Traversal vulnerability in Erlang OTP (stdlib zip module) allows writing files outside the intended extraction directory via a crafted zip archive.
zip:unzip/1,2 and zip:extract/1,2 validate entry paths using zip:check_dir_level/2, which tracks directory depth as a running integer counter: .. decrements it, normal path components increment it. The caller rejects only paths where the final counter value is less than zero. A path such as ../x/y causes the counter to go negative mid-traversal then recover to zero, passing validation while resolving to a location outside the extraction directory when joined with the current working directory via add_cwd.
This vulnerability is associated with program file lib/stdlib/src/zip.erl.
This issue affects OTP from OTP 27.1 before OTP 27.3.4.15, OTP 28.5.0.4, and OTP 29.0.4, corresponding to stdlib from 6.1 before 6.2.2.4, 7.3.0.1, and 8.0.3.
Improper Handling of Exceptional Conditions vulnerability in Erlang OTP erts (epmd) allows an unauthenticated remote attacker to permanently terminate the Erlang Port Mapper Daemon (epmd) via connection slot exhaustion.
The do_accept function in erts/epmd/src/epmd_srv.c calls epmd_cleanup_exit() when accept(2) returns EMFILE (per-process file descriptor limit reached) or ENFILE (system-wide file descriptor limit reached), rather than treating these as recoverable conditions. An attacker can exhaust epmd's file descriptor slots by holding many TCP connections open while periodically sending a single byte to reset the idle timeout, then causing accept(2) to return EMFILE, which kills the daemon. epmd has no per-source-IP connection cap, making the attack feasible from a single source.
On Debian/Ubuntu default packaging the impact is amplified: the systemd unit inherits a low file descriptor soft limit, and repeated daemon deaths trigger systemd's start-rate-limit, permanently failing both epmd.service and epmd.socket and requiring manual operator intervention to recover.
This issue affects OTP from OTP 17.0 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15.