CVE Catalog

CVE-2026-77805

HighCVSS 7.9
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.06%

0th percentile - higher than 0% of all known CVEs

Summary

In Progress Telerik Fiddler Classic for Windows prior to version 6.0.20262.10021, the integrity check for external helper tools is insufficient. The application only verifies the Authenticode signature and publisher name, not that the file is the specific executable shipped with the product. A local attacker with low privileges can replace a helper executable with another validly signed binary from an allow-listed publisher, causing it to be executed, including with Administrator privileges.

Risk Assessment

Risk of privilege escalation and execution of unintended code on workstations using Fiddler Classic. The attack requires user interaction but can lead to full system compromise.

Recommendation

Update Fiddler Classic to version 6.0.20262.10021 or later. Restrict local access to systems running Fiddler and educate users to pay attention to elevation prompt details.

Related vulnerabilities

Original NVD description (English source)

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, the integrity check applied to the external helper tools launched by the application is insufficient. Before executing a helper tool, the application only verifies that the file carries a valid Authenticode signature whose certificate subject name matches a broad allow list of publisher name fragments, rather than verifying that the file is the specific executable shipped with that version of the product. A local threat actor with low privileges who replaces one of these helper executables with any other validly signed binary from an allow-listed publisher can cause the substituted binary to be executed by the application, including with Administrator privileges for the tools that request elevation, resulting in privilege escalation and execution of unintended code. Successful exploitation requires the user to launch the affected external tool and to approve the elevation prompt without noticing that it refers to a different executable.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS