{"schema":"threatline.record/2","record":{"id":"CVE-2026-77804","aliases":[],"summary":"Time-of-check Time-of-use (TOCTOU) Race Condition in Root Certificate Installation in Progress® Telerik® Fiddler® Classic","details":"In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, a time-of-check time-of-use (TOCTOU) race condition exists in the installation of the HTTPS interception root certificate into the Local Computer certificate store. Fiddler writes the certificate to a temporary file in a user-writable location and then launches the external TrustCert helper application, which elevates and imports the certificate from that file. A local threat actor with low privileges who replaces the temporary file between the time it is written and the time the elevated helper reads it can cause an attacker-supplied root certificate to be installed in the Local Computer Trusted Root Certification Authorities store, enabling subsequent interception and modification of TLS-protected traffic on the machine. Successful exploitation requires the user to initiate the certificate trust operation and approve the elevation prompt.","categories":["Unclassified"],"product":"Progress® Telerik® Fiddler® Classic","vendor":"Progress Software","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-77804","source_modified_at":"2026-10-06T17:49:23.338Z","fetched_at":"2026-10-23T18:52:38.922436Z","product":"Progress® Telerik® Fiddler® Classic","vendor":"Progress Software","versions":[{"status":"affected","version":"1.0.0","lessThan":"6.0.20262.10021","versionType":"custom"}],"defaultStatus":"unaffected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-77804","source_modified_at":"2026-10-06T17:49:23.338Z","fetched_at":"2026-10-23T18:52:38.922436Z","package":{"name":"Progress® Telerik® Fiddler® Classic","ecosystem":null},"version":"6.0.20262.10021","basis":"first unaffected version stated in the CVE record"}],"cvss":6.6,"severity":"Medium","kev":{"listed":false},"epss":{"probability":0.00058,"percentile":0.00005,"score_date":"2026-10-23"},"published_at":"2026-10-05T12:40:26.811Z","modified_at":"2026-10-06T17:49:23.338Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-77804","fetched_at":"2026-10-23T18:52:38.922436Z","source_modified_at":"2026-10-06T17:49:23.338Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-77804","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","EPSS"],"references":[{"source":"CVE List","url":"https://docs.telerik.com/fiddler/knowledge-base/kb-security-root-certificate-installation-toctou-cve-2026-77804","tags":["vendor-advisory"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"no","technical_impact":"total","assessed_at":"2026-10-06T17:49:19.748248Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":null,"confidence":"unknown","reviewed":false},"change_timestamp":"2026-10-06T17:49:23.338Z","content_hash":"c955e8330d038f154eead1267f615ee93f2d32e64095a46d1f6c9c26bf7e41c5"}}