Tracking: CVE-2026-58483
Severity: High
Who is affected
mcp-searxng before 1.7.1, when a caller can invoke web_url_read against an attacker-controlled response. The reported HTTP deployment permits unauthenticated access; other transports require their own reachability assessment.
How the attack works
readUrlContent treats a missing Content-Length as inconclusive, then reads the entire body with .text() and converts it using NodeHtmlMarkdown. A response that is excessively large can consume memory during buffering and CPU during conversion.
The attacker controls the destination or its response, while the MCP server pays the processing cost. A timeout alone does not impose a reliable byte or conversion-work limit.
What to do
- Upgrade to 1.7.1 or later and restart the server.
- Restrict tool callers and outbound destinations. Apply response-byte, processing-time, and concurrency budgets as additional controls.
- Review unusually large URL reads, conversion stalls, memory growth, and process restarts. Block known abusive destinations while investigating.