Executive brief
mcp-searxng is a tool that integrates SearXNG search functionality with MCP (Model Context Protocol) clients. When configured with HTTP Basic Authentication credentials, the tool exposes these credentials—including username and password—through server startup logs, MCP notification messages, and JSON-RPC error responses. An attacker with access to server logs or an MCP client connection can recover credentials and use them to access the underlying SearXNG instance.
Technical details
The vulnerability is a credential exposure flaw in mcp-searxng 1.11.0. The root cause is the failure to apply the existing redactSearxngInstanceUrl() redaction function before logging and error handling. The SEARXNG_URL environment variable contains credentials in the format http://username:password@host. These credentials are exposed in three paths: (1) startup console output via stderr, (2) MCP logging notifications sent to connected clients, and (3) JSON-RPC error responses when URL validation fails. The attack vector is local (via server logs) or requires an MCP client connection (network). No authentication bypass is needed—credentials are leaked passively. The issue is marked as patched in version 1.12.0.
Affected products
- Ihor Sokoliuk mcp-searxng 1.11.0
Timeline
- 2026-07-26: disclosed
- 2026-08-19: advisory
- 2026-08-19: patched: Patched in version 1.12.0