{"id":"CVE-2026-42791","summary":"OCSP responder certificate validity period not checked in public_key","details":"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.\n\nOCSP 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.\n\nThis 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.\n\nThis issue affects OTP from OTP 27.0 before OTP 27.3.4.12, 28.5.0.1, and 29.0.1 corresponding to public_key from 1.16 before 1.17.1.3, 1.20.3.1, and 1.21.1.","aliases":["EEF-CVE-2026-42791","GHSA-cjxj-wj6x-3fff"],"modified":"2026-07-15T01:49:04.278021103Z","published":"2026-05-27T12:23:13.584Z","related":["SUSE-SU-2026:22082-1","openSUSE-SU-2026:10947-1","openSUSE-SU-2026:20907-1"],"database_specific":{"cwe_ids":["CWE-295","CWE-672"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42791.json","unresolved_ranges":[{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"1.16"},{"fixed":"*"},{"introduced":"27.0"},{"fixed":"*"},{"introduced":"2b1a742c651b90f8a7a1fb2ddde73f29915ea376"},{"fixed":"*"}]}],"cna_assigner":"EEF"},"references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-42791.html"},{"type":"WEB","url":"https://github.com"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-42791"},{"type":"WEB","url":"https://www.erlang.org/doc/system/versions.html#order-of-versions"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42791.json"},{"type":"ADVISORY","url":"https://github.com/erlang/otp/security/advisories/GHSA-cjxj-wj6x-3fff"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42791"},{"type":"FIX","url":"https://github.com/erlang/otp/commit/7995f1fdaee3da569bb810358ce0f546471d169b"},{"type":"FIX","url":"https://github.com/erlang/otp/commit/b3870e02405c709a872b01ba6086065620cdfe76"},{"type":"PACKAGE","url":"https://github.com/erlang/otp"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/erlang/otp","events":[{"introduced":"601a012837ea0a5c8095bf24223132824177124d"},{"fixed":"a2394acad3e3b8fa74d40905cb79bac2ab68258a"},{"introduced":"9e6f6742c4d9e9915ee8af0dcb7d97cf1f836116"},{"fixed":"5770157eabdd4e8b0b83d64fd8b207c0150c2b64"},{"introduced":"550d7b7898706c7822362c42e7b93120c1d1f29a"},{"fixed":"f26c7e590c5d1b3afa0dee38093442df117822e3"},{"fixed":"7995f1fdaee3da569bb810358ce0f546471d169b"},{"fixed":"b3870e02405c709a872b01ba6086065620cdfe76"}],"database_specific":{"extracted_events":[{"introduced":"27.0"},{"fixed":"27.3.4.12"},{"introduced":"28.0"},{"fixed":"28.5.0.1"},{"introduced":"29.0"},{"fixed":"29.0.1"}],"source":["CPE_RANGE","REFERENCES"],"cpe":"cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"}}],"versions":["patch-base-27","OTP-27.3.4","patch-base-28","OTP-28.5","OTP-28.4","OTP-29.0","OTP-27.3.4.9","OTP-27.0","OTP-27.3.4.11","OTP-27.3.4.10","OTP-28.0","OTP-27.3.4.8","OTP-27.3.4.6","OTP-27.3.4.7","OTP-27.3","OTP-27.3.4.5","OTP-27.3.4.4","OTP-28.1","OTP-27.3.4.3","OTP-27.3.3","OTP-27.3.4.2","OTP-27.3.4.1","OTP-27.3.2","OTP-27.2","OTP-27.3.1","OTP-27.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42791.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N"}]}