{"schema":"threatline.record/2","record":{"id":"CVE-2026-91187","aliases":["GHSA-rj24-g8cc-g7g2"],"summary":"Improper Verification of Cryptographic Signature in dashbit nimble_zta Cloudflare strategy","details":"Improper Verification of Cryptographic Signature vulnerability in dashbit nimble_zta allows an unauthenticated remote attacker to authenticate as an arbitrary Cloudflare service token. Applications using the Cloudflare Zero Trust authentication strategy are affected.\n\nverify_token/2 in lib/nimble_zta/cloudflare.ex matches the result of JOSE.JWT.verify/2 against {_, token, _s}, which discards the boolean verification result and returns the decoded token after a failed signature check. The attacker sends a forged JWT in the cf-access-jwt-assertion header, carrying the expected iss claim and the seven service token claims. verify_iss/2 reads the iss claim from the forged token, so it rejects nothing, and the service token path then returns those claims as the authenticated identity.\n\nThis issue affects nimble_zta: from 0.1.2 before 0.1.3.","categories":["Unclassified"],"product":"nimble_zta","vendor":"dashbit","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-91187","source_modified_at":"2026-09-24T14:47:30.520Z","fetched_at":"2026-10-23T18:52:38.922436Z","product":"nimble_zta","vendor":"dashbit","versions":[{"lessThan":"0.1.3","status":"affected","version":"0.1.2","versionType":"semver"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-91187","source_modified_at":"2026-09-24T14:47:30.520Z","fetched_at":"2026-10-23T18:52:38.922436Z","product":"nimble_zta","vendor":"dashbit","versions":[{"lessThan":"6458fd18a5ba41166d4973214c519e98fe05b72d","status":"affected","version":"bc004b70985ae5763901baab3a4e204047899768","versionType":"git"}],"defaultStatus":"unaffected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-91187","source_modified_at":"2026-09-24T14:47:30.520Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"nimble_zta","ecosystem":null},"version":"0.1.3","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-91187","source_modified_at":"2026-09-24T14:47:30.520Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"nimble_zta","ecosystem":null},"version":"6458fd18a5ba41166d4973214c519e98fe05b72d","basis":"first unaffected version stated in the CVE record"}],"cvss":9.3,"severity":"Critical","kev":{"listed":false},"epss":{"probability":0.00303,"percentile":0.21921,"score_date":"2026-10-23"},"published_at":"2026-09-24T13:20:52.974Z","modified_at":"2026-09-24T14:47:30.520Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-91187","fetched_at":"2026-10-23T18:52:38.922436Z","source_modified_at":"2026-09-24T14:47:30.520Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-91187","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/dashbitco/nimble_zta/security/advisories/GHSA-rj24-g8cc-g7g2","tags":["related","vendor-advisory"]},{"source":"CVE List","url":"https://cna.erlef.org/cves/CVE-2026-91187.html","tags":["related"]},{"source":"CVE List","url":"https://osv.dev/vulnerability/EEF-CVE-2026-91187","tags":["related"]},{"source":"CVE List","url":"https://github.com/dashbitco/nimble_zta/commit/bc004b70985ae5763901baab3a4e204047899768","tags":["related"]},{"source":"CVE List","url":"https://github.com/dashbitco/nimble_zta/commit/6458fd18a5ba41166d4973214c519e98fe05b72d","tags":["patch"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"yes","technical_impact":"partial","assessed_at":"2026-09-24T14:43:06.738544Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":null,"confidence":"unknown","reviewed":false},"change_timestamp":"2026-09-24T14:47:30.520Z","content_hash":"9ebb8f1be00e35eaca26d6629246cd3cbfcecd6619c3efb60ac392bd39146354"}}