{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-77804","assignerOrgId":"f9fea0b6-671e-4eea-8fde-31911902ae05","state":"PUBLISHED","assignerShortName":"ProgressSoftware","dateReserved":"2026-08-21T13:37:35.057Z","datePublished":"2026-10-05T12:40:26.811Z","dateUpdated":"2026-10-06T17:49:23.338Z"},"containers":{"cna":{"providerMetadata":{"orgId":"f9fea0b6-671e-4eea-8fde-31911902ae05","shortName":"ProgressSoftware","dateUpdated":"2026-10-05T12:40:26.811Z"},"title":"Time-of-check Time-of-use (TOCTOU) Race Condition in Root Certificate Installation in Progress® Telerik® Fiddler® Classic","problemTypes":[{"descriptions":[{"lang":"en","cweId":"CWE-367","description":"CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition","type":"CWE"}]}],"impacts":[{"capecId":"CAPEC-29","descriptions":[{"lang":"en","value":"CAPEC-29 Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions"}]}],"affected":[{"vendor":"Progress Software","product":"Progress® Telerik® Fiddler® Classic","platforms":["Windows"],"versions":[{"status":"affected","version":"1.0.0","lessThan":"6.0.20262.10021","versionType":"custom"}],"defaultStatus":"unaffected"}],"descriptions":[{"lang":"en","value":"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.","supportingMedia":[{"type":"text/html","base64":false,"value":"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."}]}],"references":[{"url":"https://docs.telerik.com/fiddler/knowledge-base/kb-security-root-certificate-installation-toctou-cve-2026-77804","tags":["vendor-advisory"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV3_1":{"version":"3.1","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"REQUIRED","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"NONE","baseSeverity":"MEDIUM","baseScore":6.6,"vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N"}}],"workarounds":[{"lang":"en","value":"Trust the Fiddler Classic certificate only in the Current User certificate store. When the application asks to install the certificate in the Local Computer (local machine) store, choose No. If a machine-wide trust is required, export the certificate to a file and import that file into the Local Computer Trusted Root Certification Authorities store manually.","supportingMedia":[{"type":"text/html","base64":false,"value":"<div>Trust the Fiddler Classic certificate only in the <b>Current User</b> certificate store. When the application asks to install the certificate in the <b>Local Computer</b> (local machine) store, choose <b>No</b>. If a machine-wide trust is required, export the certificate to a file and import that file into the Local Computer Trusted Root Certification Authorities store manually.</div>"}]}],"credits":[{"lang":"en","value":"NATO Cyber Security Centre (NCSC)","type":"finder"}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"Vulnogram 0.2.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-06T17:49:19.748248Z","id":"CVE-2026-77804","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-10-06T17:49:23.338Z"}}]}}