CVE-2026-6874 Details

A DNS rebinding vulnerability has been identified in ericc-ch copilot-api versions through 0.7.0. The issue arises in the Header Handler component, specifically within the /token file. The vulnerability allows remote attackers to manipulate the Host header of incoming requests, bypassing the browser's same-origin policy. This manipulation can be exploited to access the copilot-api running on localhost:4141, stealing the Copilot Bearer token, which is then exfiltrated to an attacker-controlled server.

To address this vulnerability, add middleware to validate the Host header of incoming requests, rejecting those with unexpected values. Replace the wildcard CORS policy with a restrictive origin policy that only allows known local origins. Bind the server to 127.0.0.1 to reduce network exposure, and add authentication to all routes to ensure that sensitive endpoints cannot be accessed without a valid API key.