Local privilege escalation via permissive helper signatures
Published Oct 5, 2026 · Updated Oct 5, 2026
Privilege escalation in Progress Telerik Fiddler Classic before 6.0.20262.10021 allows local users to run substituted helper tools as Administrator. Before launching a helper, the application accepts a valid Authenticode signature with an allowed publisher-name fragment instead of verifying the expected executable. Exploitation requires replacement of a helper file, a user to launch that tool, and approval of an elevation prompt naming the substituted executable.
Summary
What happened
Privilege escalation in Progress Telerik Fiddler Classic before 6.0.20262.10021 allows local users to run substituted helper tools as Administrator. Before launching a helper, the application accepts a valid Authenticode signature with an allowed publisher-name fragment instead of verifying the expected executable. Exploitation requires replacement of a helper file, a user to launch that tool, and approval of an elevation prompt naming the substituted executable.
The record
- CVE
- CVE-2026-77805
- Published
- Oct 5, 2026
- Updated
- Oct 5, 2026
- Vendor
- Progress Software Corporation
- Product
- Progress Telerik Fiddler Classic
- Classifications
- T1574
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Oct 5, 2026CVE publishedPublication date reported by the CVE source.
- Oct 5, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=1.0.0 <6.0.20262.10021
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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