mcp-searxng has a hardened-mode URL-reading feature intended to prevent web_url_read from reaching private or internal network resources. PR #79 appears to address one SSRF class: hostnames that resolve to private or internal addresses under hardened mode. I tested PR #79 locally and confirmed that it blocks the DNS-resolves-to-loopback case. However, several other hardened-mode SSRF bypasses still appear to remain: Redirects from an allowed first-hop URL to a loopback/internal URL are …
The web_url_read tool fetches a caller-supplied URL server-side and converts it to markdown. An SSRF guard (assertUrlAllowed, which blocks private/loopback/metadata addresses) exists but runs only when MCP_HTTP_HARDEN=true, which is off by default. So in the default configuration there is no internal-address filtering, and an attacker who can influence the URL can make the server fetch internal services and cloud metadata and return their content. Confirmed on 1.1.0 (default config): web_url_read …
mcp-searxng version 1.11.0 exposes SearXNG Basic Authentication credentials embedded in the SEARXNG_URL environment variable. When the server starts in STDIO mode and an MCP client connects, the complete SEARXNG_URL, including its username and password, is sent to the client through an MCP notifications/message logging notification. Additionally, when URL validation fails, the complete credential-bearing URL is included in the configuration error. This error is logged through MCP and returned to the …
The web_url_read MCP tool in mcp-searxng enforces its 5 MiB response-size limit exclusively by inspecting the Content-Length header of a preliminary HEAD request. When a server omits Content-Length — a standard HTTP practice — checkContentLength() returns null, the guard condition short-circuits to false, and response.text() loads the entire response body into memory without any byte cap. An unauthenticated attacker who controls or can redirect to an HTTP endpoint can force …
The web_url_read MCP tool in mcp-searxng is vulnerable to Server-Side Request Forgery (SSRF) via DNS rebinding bypass. The assertUrlAllowed() function at src/url-reader.ts:85-93 validates only the syntactic hostname string against a private IP/hostname blocklist without performing DNS resolution. An attacker who controls a domain that resolves to a private or loopback IP address (e.g., via a wildcard DNS service like nip.io, or a custom DNS entry) can bypass the security check …