CVE-2026-36615 Details

A buffer leak vulnerability has been identified in the Mercusys AC12G (EU) V1 router, specifically in the firmware version AC12G(EU)_V1_200909. The vulnerability arises from an undocumented endpoint, '/agileconfigreset', which is accessible without authentication. This endpoint leaks internal buffer contents, including parsed HTTP headers from the current request, to unauthenticated attackers on the adjacent network. The leaked data is formatted in a null-separated internal style and is sent as a malformed response that violates HTTP protocol standards.

To address this vulnerability, the undocumented '/agileconfigreset' endpoint should be removed from production firmware. If it must remain, authentication should be required, and proper HTTP error codes should be returned. Additionally, response buffers should be initialized before use.