{"cve":{"cve_id":"CVE-2026-42791","is_kev":false,"kev_date_added":null,"kev_vendor_project":null,"kev_product":null,"kev_vulnerability_name":null,"kev_short_description":null,"kev_required_action":null,"kev_due_date":null,"kev_known_ransomware":null,"kev_notes":null,"kev_cwes":null,"epss_score":0.00316,"epss_percentile":0.23152,"epss_as_of":"2026-06-23","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, 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.","published_at":"2026-05-27T12:23:13.584000Z","last_modified_at":null,"cvss_v3_score":null,"cvss_v3_vector":null,"cvss_v3_severity":null,"cvss_v4_score":6.3,"cvss_v4_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","cvss_v4_severity":"MEDIUM","ssvc_decision":null,"ssvc_exploitation":null,"ssvc_automatable":null,"ssvc_technical_impact":null,"cwes":["CWE-295","CWE-672"],"nvd_references":["https://github.com/erlang/otp/security/advisories/GHSA-cjxj-wj6x-3fff","https://cna.erlef.org/cves/CVE-2026-42791.html","https://osv.dev/vulnerability/EEF-CVE-2026-42791","https://www.erlang.org/doc/system/versions.html#order-of-versions","https://github.com/erlang/otp/commit/7995f1fdaee3da569bb810358ce0f546471d169b","https://github.com/erlang/otp/commit/b3870e02405c709a872b01ba6086065620cdfe76"],"vuln_status":null,"trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-06-24T00:09:39.878444Z","updated_at":"2026-06-28T23:30:21.418447Z"},"effective_severity":"MEDIUM","badges":[],"impact_analysis":[],"cvss_v3_decoded":{"version":null,"metrics":[]},"cvss_v4_decoded":{"version":"4.0","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"H","value_label":"High"},{"metric":"AT","name":"Attack Requirements","value":"P","value_label":"Present"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"VC","name":"Confidentiality (Vulnerable System)","value":"N","value_label":"None"},{"metric":"VI","name":"Integrity (Vulnerable System)","value":"L","value_label":"Low"},{"metric":"VA","name":"Availability (Vulnerable System)","value":"N","value_label":"None"},{"metric":"SC","name":"Confidentiality (Subsequent System)","value":"L","value_label":"Low"},{"metric":"SI","name":"Integrity (Subsequent System)","value":"L","value_label":"Low"},{"metric":"SA","name":"Availability (Subsequent System)","value":"N","value_label":"None"}]},"affected":[{"vendor_slug":"erlang","vendor_name":"erlang","product_slug":"erlang-otp","product_name":"erlang/otp","version_start":null,"version_start_inclusive":null,"version_end":null,"version_end_inclusive":null,"cpe23_uri":"cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"}],"exploit_refs":[],"news":[],"references":[{"url":"https://github.com/erlang/otp/security/advisories/GHSA-cjxj-wj6x-3fff","source_type":"VENDOR_ADVISORY","tags":["advisory"]},{"url":"https://cna.erlef.org/cves/CVE-2026-42791.html","source_type":"MISC","tags":[]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-42791","source_type":"MISC","tags":[]},{"url":"https://www.erlang.org/doc/system/versions.html#order-of-versions","source_type":"MISC","tags":[]},{"url":"https://github.com/erlang/otp/commit/7995f1fdaee3da569bb810358ce0f546471d169b","source_type":"PATCH","tags":["patch"]},{"url":"https://github.com/erlang/otp/commit/b3870e02405c709a872b01ba6086065620cdfe76","source_type":"PATCH","tags":["patch"]}],"timeline":[{"type":"published","at":"2026-05-27T12:23:13.584000Z","label":"CVE published","source":null},{"type":"cvss_changed","at":"2026-06-28T17:54:12.493575Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:54:12.493575Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:54:12.493575Z","label":"CVSS score revised","source":"cvelistv5"}]}