CVE-2026-55953
HighCVSS 7.4Exploitation Probability (EPSS)
Low risk14th percentile - higher than 14% of all known CVEs
Summary
The TLS 1.2 (and earlier) and DTLS client in Erlang/OTP does not verify that the cipher suite selected by the server in ServerHello was among the suites offered by the client. An on-path attacker can select an anonymous cipher suite, bypassing certificate and hostname verification, allowing interception and modification of traffic.
Risk Assessment
The organization is exposed to man-in-the-middle attacks where an attacker can impersonate the server, read and modify data sent by the client, potentially leading to data breaches or integrity compromise.
Recommendation
Upgrade Erlang/OTP to version 27.3.4.15, 28.5.0.4, or 29.0.4 (or later) and ensure TLS clients use TLS 1.3, which includes the proper check.
Other vulnerabilities in Erlang/OTP
See all- CVE-2026-28808Critical
An incorrect authorization vulnerability in Erlang OTP (inets modules) allows unauthenticated access to CGI scripts protected by directory rules when served via script_alias. The path mismatch between access control evaluation and script execution allows bypassing protections.
- CVE-2026-23941Critical
In Erlang OTP (inets httpd module), an HTTP Request Smuggling vulnerability exists. The server does not reject or normalize duplicate Content-Length headers. The first value is used, while common proxies use the last, enabling front-end/back-end desynchronization and injection of attacker-controlled bytes as the start of the next request.
- CVE-2025-32433CriticalActively exploited
Erlang/OTP prior to versions OTP-27.3.3, OTP-26.2.5.11, and OTP-25.3.2.20 contains a vulnerability in the SSH server that may allow an attacker to perform unauthenticated remote code execution (RCE). By exploiting a flaw in SSH protocol message handling, a malicious actor could gain unauthorized access and execute arbitrary commands without valid credentials.
- CVE-2016-10253Critical
An issue was discovered in Erlang/OTP 18.x related to the generation of compiled regular expressions, which is vulnerable to a heap overflow. Regular expressions using a malformed extpattern can indirectly specify an offset used as an array index.
- CVE-2026-75538High
In Erlang/OTP, when using the inet driver with {packet,4} mode, an attacker connecting to an open TCP port can exploit a signed overflow in packet length calculation, potentially overflowing the receive buffer and crashing the BEAM VM.
- CVE-2026-74835High
The httpd HTTP server in the inets application fails to enforce a configured body-size limit on chunked requests. This may allow sending very large requests, potentially leading to server overload.
- CVE-2026-73812High
The check_header/3 function in httpd rejects duplicate Content-Length but does not check for the co-presence of Transfer-Encoding and Content-Length, which can lead to request smuggling desynchronization between front-end and back-end.
- CVE-2026-73276High
Gracefulness code ignored cases that should be rejected, resulting in possible HTTP Request Smuggling opportunities.
- CVE-2026-58227High
A vulnerability in the Erlang/OTP SSL application allows memory exhaustion by sending a crafted certificate chain during TLS/DTLS handshake. Lack of cycle detection in the certificate chain building function causes unbounded recursion, leading to BEAM node crash.
- CVE-2026-55737High
In Erlang OTP, a signed to unsigned conversion error and out-of-bounds heap write vulnerability exists when decoding a crafted ETF binary via binary_to_term/1. This can corrupt the BEAM heap pointer and crash the virtual machine.
Original NVD description (English source)
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.