CVE-2026-89422

Ein Angreifer kann mehrere Schwachstellen in Erlang/OTP ausnutzen, um einen Denial of Service Angriff durchzuführen, Sicherheitsmaßnahmen zu umgehen und Daten zu manipulieren oder offenzulegen.

## Summary Key Exchange without Entity Authentication vulnerability in Erlang/OTP ssl allows a peer that answers a TLS 1.3 client connection to impersonate the intended server. A `pre_shared_key` extension in the `ServerHello` that the client never offered causes the client to complete the handshake without validating the server's certificate, so `ssl:connect` returns `{ok, Socket}` against a peer holding no certificate, no private key and no prior session. `tls_client_connection_1_3:handle_server_hello/2` passes the received extension to `tls_gen_connection_1_3:handle_resumption/2`, which sets `resumption = true` on its mere presence without checking that the client offered a PSK. `tls_handshake_1_3:get_pre_shared_key/4` meanwhile falls back to the all-zero "no PSK" value and keys the handshake with the ordinary non-PSK schedule, so the attacker's own ephemeral key suffices. The resumption flag then routes `maybe_resumption/1` straight to `wait_finished`, skipping the certificate-handling states, so certificate path validation, `verify_fun`, hostname verification, `partial_chain`, CRL checking and OCSP stapling are all bypassed. The default client configuration is affected; clients restricted to TLS 1.2 are not. This issue affects OTP from OTP 22.2 before OTP 27.3.4.18, OTP 28.5.0.7, and OTP 29.1.1, corresponding to ssl from 9.5 before 11.2.12.13, 11.6.0.6, and 11.7.7. ## Impact An attacker that answers a TLS 1.3 client connection, either as the host the client dials or as an on-path attacker, completes the handshake as the intended server and holds all traffic keys. It can read everything the application sends, including credentials, tokens and request bodies, and forge every response. Any consumer of `ssl:connect` that negotiates TLS 1.3 is affected, including `httpc` over HTTPS, database and messaging client libraries, and TLS distribution clients. ## Workarounds Restrict affected clients to TLS 1.2 by setting `{versions, ['tlsv1.2']}` in the client's `ssl` options. This avoids the vulnerable code path at the cost of losing TLS 1.3. No configuration both keeps TLS 1.3 and mitigates the issue.