CVE-2026-77804 (GCVE-0-2026-77804)

Vulnerability from cvelistv5 – Published: 2026-10-05 12:40 – Updated: 2026-10-06 17:49
VLAI
Title
Time-of-check Time-of-use (TOCTOU) Race Condition in Root Certificate Installation in Progress® Telerik® Fiddler® Classic
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 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.
Severity
6.6 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-06 17:49 UTC
CWE
  • CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition
Assigner
ProgressSoftware CNA under the mitre root
CNA scorecard B 78/100 over 121 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Progress Software Progress® Telerik® Fiddler® Classic Affected: 1.0.0 , < 6.0.20262.10021 (custom)
guessed Create a notification for this product.
Credits
NATO Cyber Security Centre (NCSC)
Show details on NVD website
To clipboard 

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