Applications calling public_key:pkix_ocsp_validate/5 directly are unconditionally affected when that function is used.
"}],"value":"For the ssl application, OCSP stapling must be enabled by setting the stapling option to staple in the TLS client options. OCSP stapling is not enabled by default.\n\nApplications calling public_key:pkix_ocsp_validate/5 directly are unconditionally affected when that function is used."}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*","versionEndExcluding":"27.3.4.12","versionStartIncluding":"27.0","vulnerable":true},{"criteria":"cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*","versionEndExcluding":"28.5.0.1","versionStartIncluding":"28.0","vulnerable":true},{"criteria":"cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*","versionEndExcluding":"29.0.1","versionStartIncluding":"29.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"remediation developer","value":"Jakub Witczak"},{"lang":"en","type":"remediation reviewer","value":"Ingela Anderton Andin"}],"descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"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 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.
"}],"value":"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."}],"impacts":[{"capecId":"CAPEC-475","descriptions":[{"lang":"en","value":"CAPEC-475 Signature Spoofing by Improper Validation"}]}],"metrics":[{"cvssV4_0":{"attackComplexity":"HIGH","attackRequirements":"PRESENT","attackVector":"NETWORK","baseScore":6.3,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"LOW","subIntegrityImpact":"LOW","userInteraction":"NONE","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-295","description":"CWE-295 Improper Certificate Validation","lang":"en","type":"CWE"},{"cweId":"CWE-672","description":"CWE-672 Operation on a Resource after Expiration or Release","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-05-27T15:41:07.758Z","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","shortName":"EEF"},"references":[{"tags":["vendor-advisory","related"],"url":"https://github.com/erlang/otp/security/advisories/GHSA-cjxj-wj6x-3fff"},{"tags":["related"],"url":"https://cna.erlef.org/cves/CVE-2026-42791.html"},{"tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-42791"},{"tags":["x_version-scheme"],"url":"https://www.erlang.org/doc/system/versions.html#order-of-versions"},{"tags":["patch"],"url":"https://github.com/erlang/otp/commit/7995f1fdaee3da569bb810358ce0f546471d169b"},{"tags":["patch"],"url":"https://github.com/erlang/otp/commit/b3870e02405c709a872b01ba6086065620cdfe76"}],"source":{"discovery":"INTERNAL"},"title":"OCSP responder certificate validity period not checked in public_key","workarounds":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"