CVE-2026-55953
Erlang/OTP’s SSL/TLS client can accept a server‑chosen cipher suite that the client never offered, allowing an attacker to use an anonymous cipher and bypass certificate checks. This flaw lets an on‑path attacker read and modify all traffic after the handshake.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Erlang/OTP SSL/TLS client versions before OTP 29.0.4, OTP 28.5.0.4, and OTP 27.3.4.15 (corresponding to ssl 5.3.4 before 11.7.4, 11.6.0.4, and 11.2.12.11).
Real-world impact
An attacker between the client and server can complete the TLS handshake with an anonymous cipher suite, bypassing all certificate verification. The attacker then gains full read/write access to the encrypted traffic.
Why this severity
The CVSS score of 9.1 reflects the high impact on confidentiality (the attacker can read all data) and the lack of authentication or integrity checks, combined with low attack complexity and no user interaction.
What to do about it
- 01Identify the current Erlang/OTP version you are running.
- 02Upgrade to OTP 29.0.4 or later, OTP 28.5.0.4 or later, or OTP 27.3.4.15 or later, which contain the patch that validates the server‑chosen cipher suite.
NVD description
Timeline
- Jul 27, 2026 · 4d agoPublishedDisclosed and added to the National Vulnerability Database.
- Jul 27, 2026 · 4d agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.
- Jul 30, 2026 · 1d agoAdvisory updatedThe NVD record was last revised.