CVE-2026-58483

mcp-searxng, a Model Context Protocol (MCP) server that gives AI assistants web search and URL-reading capabilities via SearXNG, contains an uncontrolled resource consumption flaw (CWE-400) in its web_url_read tool. In versions prior to 1.7.1, the URL reader's checkContentLength() preflight treats a missing Content-Length header as inconclusive, and both the normal and error code paths then consume the entire response body with response.text(), so a malicious or misbehaving web server can return a huge body without a Content-Length header and bypass the URL_READ_MAX_CONTENT_LENGTH_BYTES limit. The resulting oversized string is additionally processed by NodeHtmlMarkdown.translate(), amplifying CPU cost, which allows an unauthenticated HTTP client interacting with the MCP server to exhaust memory and CPU and cause denial of service. Anyone running the mcp-searxng MCP server on a version before 1.7.1 is affected. The issue is fixed in version 1.7.1, and no public proof of concept or known exploitation in the wild has been reported.

What to do: Upgrade mcp-searxng to version 1.7.1 or later, which enforces the content-length limit even when the Content-Length header is absent. Until patched, restrict access to the MCP server endpoint (do not expose it to unauthenticated HTTP clients), and consider placing it behind a rate-limiting or body-limiting reverse proxy. Monitor Node process memory and CPU for unexpected spikes that could indicate abuse of the web_url_read tool.