CVE-2026-54887

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 OTP 29.0.3, OTP 28.5.0.3 and OTP 27.3.4.14, corresponding to ssl from 8.2 before 11.7.3, 11.6.0.3 and 11.2.12.10.

• CWE-1394

• https://cna.erlef.org/cves/CVE-2026-54887.htmlVendor Advisory
• https://github.com/erlang/otp/commit/888e3bcd72d5406016b9e0de741026bc2a6f114dPatch
• https://github.com/erlang/otp/security/advisories/GHSA-p2m2-3c2w-8jp8Vendor Advisory
• https://osv.dev/vulnerability/EEF-CVE-2026-54887Third Party Advisory
• https://www.erlang.org/doc/system/versions.html#order-of-versionsRelease Notes

Published

Jul 2, 2026

Last Modified

Jul 24, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
• Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
• PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
• AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.

• CVE-2026-5486The Unlimited Elements for Elementor plugin for WordPress is…6.5
• CVE-2026-5487DriveLock Directory Traversal Information Disclosure Vulnera…7.5
• CVE-2026-54876Issue summary: A malicious TLS server can cause a memory lea…7.5
• CVE-2026-5488The ExactMetrics – Google Analytics Dashboard for WordPress …5.3
• CVE-2026-54885Server-Side Request Forgery vulnerability in malach-it Borut…6.9
• CVE-2026-54886Loop with Unreachable Exit Condition ('Infinite Loop') vulne…4.3
• CVE-2026-54888Uncontrolled Recursion vulnerability in leandrocp mdex allow…6.9
• CVE-2026-54889Improper Neutralization of Input During Web Page Generation …5.1
• CVE-2026-5489DriveLock Directory Traversal Information Disclosure Vulnera…5.3
• CVE-2026-54890Integer Underflow (Wrap or Wraparound) vulnerability in erla…7.5
• CVE-2026-54891Improper Enforcement of Message Integrity During Transmissio…3.7
• CVE-2026-54892Inefficient algorithmic complexity in Plug's nested-paramete…8.7