Progress Telerik Fiddler Everywhere CVEs and Security Vulnerabilities

CVE-2026-86158

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

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.

CVSS 3.1 · 7.7 High EPSS < 1% KEV · Not listed

Vendors

Progress Software

Products

Progress Telerik Fiddler Everywhere

CVE-2026-86157

Exposure of Privileged IPC Functionality in Progress Telerik Fiddler Everywhere

Exposure of privileged IPC functionality in Progress Telerik Fiddler Everywhere before version 8.2.0 allows a local, low-privileged attacker who can modify application launch parameters and persuade a user to start the application to replace the application UI or settings with attacker-controlled content. Successful exploitation could result in disclosure of OAuth authentication tokens, execution of locally accessible programs, or unauthorized modification of application-generated configuration files.

CVSS 3.1 · 5.6 Medium EPSS < 1% KEV · Not listed