Improper Certificate Validation in Erlang OTP - CVE-2026-105236
Published: October 14, 2026
Vulnerability details
The vulnerability allows a remote attacker to bypass client certificate authentication for a protected SNI virtual host.
The vulnerability exists due to improper certificate validation in the Erlang/OTP ssl TLS 1.2 session resumption implementation when accepting session-ID resumptions across SNI virtual hosts. A remote attacker can resume a session established at a lower-trust SNI name at a higher-trust SNI name without the cached client certificate being validated against the higher-trust certificate authority to bypass client certificate authentication for a protected SNI virtual host.
Exploitation requires at least two SNI names on one listener sharing a server certificate but using distinct client certificate authorities, negotiated TLS 1.2, and enabled session reuse. A legitimate client certificate for the lower-trust SNI name is required, but no certificate trusted by the protected SNI name is needed. TLS 1.3 is not affected.