Improper Validation of Consistency within Input vulnerability in Erlang OTP ssl (tls_handshake_1_3…

Why it is Amber

• CVSS 8.2 high
• Remotely exploitable without logging in

References

• https://cna.erlef.org/cves/CVE-2026-94200.html
• https://github.com/erlang/otp/commit/00a333bcf2800b69f540369b54167e897dae7219
• https://github.com/erlang/otp/commit/0abe6f66db0d295cd06b0efab3bdb3caa2803930
• https://github.com/erlang/otp/commit/66febc190e6dc42a5c4aedbfe250bf9a2edc2d5e
• https://github.com/erlang/otp/commit/cd0334854bf3ef56dc16f9fb728efe88fb05c4ac
• https://github.com/erlang/otp/security/advisories/GHSA-m5mh-q53w-67jq
• https://osv.dev/vulnerability/EEF-CVE-2026-94200
• https://www.erlang.org/doc/system/versions.html#order-of-versions

Original description

Improper Validation of Consistency within Input vulnerability in Erlang OTP ssl (tls_handshake_1_3, ssl_handshake and tls_client_ticket_store modules) allows a malicious TLS 1.3 server to cause a denial of service of the ssl application on the client node. The TLS 1.3 client decodes the extensions of a NewSessionTicket message as if they came from EncryptedExtensions. It therefore accepts a 0-length early_data extension, a form that is only valid in ClientHello and EncryptedExtensions. With {session_tickets, auto}, the client stores the ticket in the node-global tls_client_ticket_store. On the next automatic resumption, tls_handshake_1_3:get_max_early_data/1 crashes the store with a case_clause. Repeated crashes can exceed the restart intensity of the ssl supervisors, which use the rest_for_one strategy, and take down ssl for all connections on the node. This issue affects OTP from OTP 23.3 before OTP 27.3.4.19, OTP 28.5.0.8, and OTP 29.1.2, corresponding to ssl from 10.3 before 11.2.12.14, 11.6.0.7, and 11.7.8.