Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_ocsp module) allows forged OCSP responses signed with an expired responder certificate to be accepted as valid.

OCSP response verification in pubkey_ocsp:verify_response/5 and pubkey_ocsp:is_authorized_responder/3 in lib/public_key/src/pubkey_ocsp.erl does not check the validity period (notBefore/notAfter) of the OCSP responder certificate. An attacker who has obtained the private key of an expired CA-designated OCSP responder certificate can forge OCSP responses that Erlang/OTP accepts as valid.

This affects TLS clients using OCSP stapling via the ssl application: a malicious or compromised server can present a revoked TLS certificate together with a forged OCSP response signed by an expired responder key, and the client will accept the revoked certificate as valid. It also affects applications calling public_key:pkix_ocsp_validate/5 directly, where the impact depends on the use case — server-side client certificate validation using this API may allow authentication bypass with a revoked client certificate.

This issue affects OTP from OTP 27.0 before OTP 29.0.1, OTP 28.5.0.1 and OTP 27.3.4.12, corresponding to public_key from 1.16 before 1.21.1, 1.20.3.1 and 1.17.1.3.

erlang27-27.1.3-2.1 on GA media

erlang: Erlang OTP public_key: Certificate chain forgery via improper trust chain validation erlang: Erlang OTP public_key: Certificate validation bypass allows hostname spoofing erlang: Erlang OTP: Authentication bypass due to improper OCSP certificate validation erlang: Erlang OTP ssh: Information disclosure via symlink resolution in SFTP erlang: erlang-inets: erlang-ftp: Erlang/OTP ftp: Server-Side Request Forgery (SSRF) via unvalidated PASV response IP address erlang: Erlang/OTP: Authentication bypass allows arbitrary code execution via improper IP address validation erlang: Erlang OTP: Denial of Service via crafted SCTP ERROR chunk erlang: Erlang OTP ssh: Denial of Service via infinite loop in SFTP channel erlang: Erlang SSL: Unauthenticated data injection during TLS handshake erlang: Erlang/OTP: Denial of Service in TLS 1.3 session ticket handling erlang: Erlang/OTP: Remote denial of service via signed length overflow in TCP driver

Security update for erlang

Affected: Ubuntu:Pro:14.04:LTS: erlang, Ubuntu:Pro:16.04:LTS: erlang, Ubuntu:Pro:18.04:LTS: erlang, Ubuntu:Pro:20.04:LTS: erlang, Ubuntu:22.04:LTS: erlang, Ubuntu:24.04:LTS: erlang, Ubuntu:25.10: erlang, Ubuntu:26.04:LTS: erlang

Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_ocsp module) allows forged OCSP responses signed with an expired responder certificate to be accepted as valid. OCSP response verification in pubkey_ocsp:verify_response/5 and pubkey_ocsp:is_authorized_responder/3 in lib/public_key/src/pubkey_ocsp.erl does not check the validity period (notBefore/notAfter) of the OCSP responder certificate. An attacker who has obtained the private key of an expired CA-designated OCSP responder certificate can forge OCSP responses that Erlang/OTP accepts as valid. This affects TLS clients using OCSP stapling via the ssl application: a malicious or compromised server can present a revoked TLS certificate together with a forged OCSP response signed by an expired responder key, and the client will accept the revoked certificate as valid. It also affects applications calling public_key:pkix_ocsp_validate/5 directly, where the impact depends on the use case — server-side client certificate validation using this API may allow authentication bypass with a revoked client certificate. This issue affects OTP from OTP 27.0 before OTP 29.0.1, OTP 28.5.0.1 and OTP 27.3.4.12, corresponding to public_key from 1.16 before 1.21.1, 1.20.3.1 and 1.17.1.3.

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Erlang/OTP ausnutzen, um Sicherheitsvorkehrungen zu umgehen.