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TI-2026-67613 Aliases CVE-2026-77804GHSA-rx7m-qprj-p54h

Race condition in Progress Telerik Fiddler Classic certificate installation

Priority LOW 30CWE-367Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
Required
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

Progress Telerik Fiddler Classic for Windows versions from 1.0.0 before 6.0.20262.10021 contain a time-of-check time-of-use race condition (CWE-367) in installing the HTTPS interception root certificate. A local attacker with low privileges who replaces the temporary certificate file after it is written can get an attacker-supplied root certificate installed in the Local Computer Trusted Root store. That certificate can then be used to intercept and modify TLS-protected traffic on the machine. Exploitation requires the user to start the certificate trust operation and approve the elevation prompt.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00066 0th percentileScored 2026-11-07
Fix Fixed Progress® Telerik® Fiddler® Classic (Progress Software): 6.0.20262.10021

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ProgressProgress® Telerik® Fiddler® Classic1.0.0 to before 6.0.20262.100216.0.20262.10021Patch availableCNA
  • Progress® Telerik® Fiddler® Classic VendorProgress Affected 1.0.0 to before 6.0.20262.10021 Fixed in 6.0.20262.10021 Patch available CNA

Remediation

Update Progress Telerik Fiddler Classic to version 6.0.20262.10021 or later, which fixes this issue.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

  • Fix · CNA Progress® Telerik® Fiddler® Classic (Progress Software) Fixed in 6.0.20262.10021

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    Progress® Telerik® Fiddler® Classic 6.0.20262.10021

    4 records Highest priority Priority LOW 4 LOW

    Other records, highest priority first

    • TI-2026-67614 Weak helper tool signature checks in Telerik Fiddler ClassicPriority LOW 35
    • TI-2026-67611 HTTP request smuggling in Progress Telerik Fiddler ClassicPriority LOW 29
    • TI-2026-67612 Telerik Fiddler Classic front-end desynchronization enables request smugglingPriority LOW 16
    Show all 4 records →

Timeline

  1. 2026-10-05 Threatist record created from CVE-2026-77804
  2. 2026-10-05 Alias added: GHSA-rx7m-qprj-p54h
  3. 2026-10-06 CISA SSVC decision points changed
  4. 2026-10-06 Priority changed: MEDIUM → LOW

References

Advisory 1

  • TI-2026-07083 Command injection in Progress LoadMaster KEVCVSS 3.1CRITICAL 9.8
  • TI-2024-06182 WhatsUp Gold HasErrors SQL Injection Authentication Bypass Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2024-04541 WhatsUp Gold GetFileWithoutZip Directory Traversal Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2024-04060 Registration Authentication Bypass Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2024-01127 LoadMaster Pre-Authenticated OS Command Injection KEVCVSS 3.1CRITICAL 10.0
  • TI-2023-20934 WS_FTP Server Ad Hoc Transfer Module .NET Deserialization Vulnerability KEVCVSS 3.1CRITICAL 10.0
See all 436 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences