CVE-2026-86249

On a brpc::Server that sets both ServerOptions.auth and ServerOptions.internal port, the HTTP built-in service exemption on internal port can be abused to bypass authentication entirely. VerifyHttpRequest() returns true without checking any credential when a built-in service is requested on internal port, and this verdict is not per - request: verification runs only for the first message of a connection and the result latches the connection. Sending a request such as GET /status to internal port first authenticates the whole connection, after which every subsequent request dispatched on the same connection is handled without ever calling VerifyHttpRequest(). This lets a remote attacker reach ordinary (non-built-in, non-tabbed) authenticated services without supplying valid credentials whenever the server uses ServerOptions.internal port together with an Authenticator. The fix restricts internal port so that it carries only built-in and Tabbed services; requests for ordinary services sent to internal port are rejected with EPREM / HTTP 403. 

Mitigation / Fix: upgrade to 1.18.0 or apply PR https://github.com/apache/brpc/pull/3525 . 

Users who rely on serving normal services on internal port must move those requests to the port passed to Server::Start().