CVE-2026-54887
MediumCVSS 6.3Exploitation Probability (EPSS)
Low risk31th percentile — higher than 31% of all known CVEs
Summary
A vulnerability in the SSL library of the DTLS server in Erlang/OTP uses a default empty cryptographic key for DTLS cookie generation during server startup. This makes cookies predictable, allowing an attacker to bypass source address verification.
Risk Assessment
An attacker who can observe network traffic can forge a DTLS cookie and send crafted packets with a spoofed source IP, leading to DTLS handshake amplification and potential DoS. The risk exists during the window from server startup to the first key rotation (0-15 seconds).
Recommendation
Immediately update Erlang/OTP to version 29.0.3, 28.5.0.3, or 27.3.4.14 (depending on the branch) and the SSL library to version 11.7.3, 11.6.0.3, or 11.2.12.10.
Original NVD description (English source)
Use of Default Cryptographic Key vulnerability in Erlang/OTP ssl (DTLS server) allows predictable DTLS cookie computation during the startup window, enabling source address verification bypass. On DTLS server startup, dtls_server_connection:initial_hello/3 initializes previous_cookie_secret to the empty binary (<<>>) instead of a random value. Because HMAC with an empty key is deterministic, anyone who observes the plaintext ClientHello can compute dtls_handshake:cookie(<<>>, IP, Port, Hello) and forge a valid DTLS cookie before the first rotation of the cookie secret. The DTLS cookie (RFC 6347 §4.2.1) is a denial-of-service mitigation that prevents spoofed source IPs from forcing the server to allocate state and perform expensive cryptographic operations; it is not an authentication mechanism. During the window from server startup until the first secret rotation (0 to 15 seconds), an attacker who can observe the plaintext ClientHello can bypass the source address verification, enabling DTLS handshake amplification with spoofed source addresses. This vulnerability is associated with program file lib/ssl/src/dtls_server_connection.erl and program routine dtls_server_connection:initial_hello/3. This issue affects OTP from OTP 20.0 before 29.0.3, 28.5.0.3 and 27.3.4.14 corresponding to ssl from 8.2 before 11.7.3, 11.6.0.3 and 11.2.12.10.