{"id":"CVE-2026-77804","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-77804","generatedAt":"2026-10-28T01:43:09.005Z","title":"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.","description":"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.","published":"2026-10-05T13:16:55.000Z","lastModified":"2026-10-06T18:16:56.000Z","status":"Awaiting Analysis","sourceIdentifier":"security@progress.com","cvss":{"version":"3.1","score":6.6,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N"},"cwe":["CWE-367"],"affected":[],"epss":{"score":0.00066,"percentile":0.00018,"date":"2026-10-26","history":[{"date":"2026-10-06","score":0.00058,"percentile":0.00004}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.07%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-05T13:16:55.000Z","detail":{"score":"6.6","severity":"MEDIUM","publishedAt":"2026-10-05T13:16:54.590Z"},"summary":"New CVE, medium severity (CVSS 6.6)."}],"references":[{"url":"https://docs.telerik.com/fiddler/knowledge-base/kb-security-root-certificate-installation-toctou-cve-2026-77804","source":"security@progress.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-77804","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}