{"id":"CVE-2026-77804","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 cer…","summary":"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 cer…","severity":"medium","cvss":6.6,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N","cwe":["CWE-367"],"vendor":"Progress Software","product":"Progress® Telerik® Fiddler® Classic","affected":["progress_telerik_fiddler_classic >= 1.0.0 < 6.0.20262.10021"],"published":"2026-10-05","updated":"2026-10-05","sourceUpdated":"2026-10-05T13:16:54.590","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-77804","references":[{"url":"https://docs.telerik.com/fiddler/knowledge-base/kb-security-root-certificate-installation-toctou-cve-2026-77804","label":"security@progress.com"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-10-05T13:20:09.439Z","slug":"CVE-2026-77804","body":"## Overview\n\nIn 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":36.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}