PYSEC-2026-2473 fast-mcp-telegram: Bearer token path traversal bypasses reserved Telegram session protection

Summary fast-mcp-telegram validates HTTP Bearer tokens by joining the raw token string into a session-file path. The verifier rejects the exact reserved token telegram, but it does not reject path separators or normalize the path before checking whether the session file exists. A remote HTTP clie...

Improper Authentication

Overview fast-mcp-telegram is a Multi-tenant Telegram gateway for AI agents — HTTP+stdio transport, 8 agent-optimized tools, MTProto User API Affected versions of this package are vulnerable to Improper Authentication via the SessionFileTokenVerifier.verifytoken process. An attacker can gain...