CVE-2026-54887— DTLS server cookie bypass during startup window due to empty initial cookie secret

DTLS server cookie bypass during startup window due to empty initial cookie secret

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.

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CWE-1394

Erlang/OTP 信任管理问题漏洞

erlang erlang/otp是erlang社区开源的一套并发编程语言及运行时系统。 Erlang存在信任管理问题漏洞，该漏洞源于默认加密密钥使用问题，导致在启动窗口期间DTLS cookie计算可预测，从而使源地址验证绕过，攻击者可利用此漏洞通过伪造的源地址进行DTLS握手放大。

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