{"affected":[{"defaultStatus":"unaffected","ecosystem":"software-id","packageName":"otp","product":"OTP","source":"CNA: EEF","vendor":"Erlang","versions":[{"changes":[{"at":"27.3.4.12","status":"unaffected"},{"at":"28.5.0.1","status":"unaffected"},{"at":"29.0.1","status":"unaffected"}],"lessThan":"*","status":"affected","version":"27.0","versionType":"otp"}]},{"defaultStatus":"unaffected","ecosystem":"otp","packageName":"public_key","product":"OTP","source":"CNA: EEF","vendor":"Erlang","versions":[{"changes":[{"at":"1.17.1.3","status":"unaffected"},{"at":"1.20.3.1","status":"unaffected"},{"at":"1.21.1","status":"unaffected"}],"lessThan":"*","status":"affected","version":"1.16","versionType":"otp"}]},{"defaultStatus":"unaffected","ecosystem":"github","packageName":"erlang/otp","product":"OTP","source":"CNA: EEF","vendor":"Erlang","versions":[{"changes":[{"at":"7995f1fdaee3da569bb810358ce0f546471d169b","status":"unaffected"},{"at":"b3870e02405c709a872b01ba6086065620cdfe76","status":"unaffected"}],"lessThan":"*","status":"affected","version":"2b1a742c651b90f8a7a1fb2ddde73f29915ea376","versionType":"git"}]}],"cveId":"CVE-2026-42791","cwes":["CWE-295","CWE-672"],"description":"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, OTP 28.5.0.1, and OTP 29.0.1, corresponding to public_key from 1.16 before 1.17.1.3, 1.20.3.1, and 1.21.1.","epss":{"date":"2026-11-10","percentile":0.24756,"score":0.00316},"exploits":[],"kev":null,"metrics":[{"score":6.3,"severity":"medium","source":"CNA: EEF","vector":"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"}],"modifiedAt":1794424275974,"publishedAt":1779884593584,"references":[{"source":"CNA: EEF","tags":["vendor-advisory","related"],"url":"https://github.com/erlang/otp/security/advisories/GHSA-cjxj-wj6x-3fff"},{"source":"CNA: EEF","tags":["related"],"url":"https://cna.erlef.org/cves/CVE-2026-42791.html"},{"source":"CNA: EEF","tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-42791"},{"source":"CNA: EEF","tags":["x_version-scheme"],"url":"https://www.erlang.org/doc/system/versions.html#order-of-versions"},{"source":"CNA: EEF","tags":["related"],"url":"https://github.com/erlang/otp/commit/2b1a742c651b90f8a7a1fb2ddde73f29915ea376"},{"source":"CNA: EEF","tags":["patch"],"url":"https://github.com/erlang/otp/commit/7995f1fdaee3da569bb810358ce0f546471d169b"},{"source":"CNA: EEF","tags":["patch"],"url":"https://github.com/erlang/otp/commit/b3870e02405c709a872b01ba6086065620cdfe76"}],"remediation":[{"kind":"workaround","source":"CNA: EEF","text":"* For TLS clients using the ssl application, disable OCSP stapling by setting {stapling, no_staple} in the client options, or switch to CRL-based revocation checking with {crl_check, true}.\n* For applications calling public_key:pkix_ocsp_validate/5 directly, validate the responder certificate's validity period in application code before calling the function."},{"kind":"fix","source":"CNA: EEF","text":"The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.","url":"https://github.com/erlang/otp/commit/7995f1fdaee3da569bb810358ce0f546471d169b"},{"kind":"fix","source":"CNA: EEF","text":"The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.","url":"https://github.com/erlang/otp/commit/b3870e02405c709a872b01ba6086065620cdfe76"}],"revision":"b9482b87fa0903ac51eb567c249f1a0652399ce544223d7bd8a62a7b10709538","sources":[{"modifiedAt":1794424275974,"name":"CNA: EEF","retrievedAt":1794427760217,"url":"https://www.cve.org/CVERecord?id=CVE-2026-42791"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1794427765402,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-42791"}],"ssvc":{"assessedAt":1779896427647,"automatable":"no","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"partial"},"status":"published","title":"OCSP responder certificate validity period not checked in public_key","updatedAt":1794427765402}