All vulnerabilities
CVE-2026-86158

Missing Authentication in the local .NET backend of Progress Telerik Fiddler Everywhere

Progress Software Progress® Telerik® Fiddler® Everywhere
Open in ThreatlineRecord JSON
CVSS
7.7High
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.09%Chance of exploitation activity in the next 30 days, higher than 0% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in8.2.0Fixed versionCVE List
Published29 Sep 2026Updated 30 Sep 2026CVE List

What fixes it

  • 8.2.0Progress® Telerik® Fiddler® EverywhereCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

Missing authentication in the local .NET backend (Fiddler.WebUi) of Progress Software Fiddler Everywhere 8.0.2 allows a local unauthenticated attacker to mint OAuth tokens and read the machine-in-the-middle root certificate through an unauthenticated localhost HTTP and SignalR RPC channel.

Text from CVE List

Affected versions 1

  • Progress® Telerik® Fiddler® Everywhereaffected: 1.0.0 before 8.2.0CVE List

References 1