CVE-2026-39974

OVERVIEW CVE-2026-39974 is a Server-Side Request Forgery (SSRF) vulnerability in n8n-MCP versions prior to 2.47.4. The vulnerability allows authenticated users with a valid AUTH_TOKEN to manipulate multi-tenant HTTP headers and cause the server to issue HTTP requests to arbitrary URLs. Response data from these requests is returned to the attacker via JSON-RPC, enabling information disclosure. The vulnerability primarily affects multi-tenant HTTP deployments where multiple operators possess valid authentication tokens or where tokens are shared with less-trusted clients. Single-tenant deployments using stdio or HTTP without multi-tenant headers remain unaffected. SEVERITY The vulnerability carries a CVSS v3.1 score of 8.5 (HIGH) with a network attack vector, low complexity, and low privilege requirements. The attack requires valid authentication but no user interaction. The scope is changed, meaning the vulnerability can impact resources beyond the vulnerable component. The primary impact is high confidentiality loss, as attackers can read response bodies from any URL the server can access, including cloud metadata endpoints (AWS IMDS, GCP, Azure, Alibaba, Oracle) and internal services. Secondary impacts include limited integrity issues. The EPSS score of 0.00031 indicates relatively low exploit probability compared to other vulnerabilities. EXPLOITATION STATUS CVE-2026-39974 is not currently listed on CISA's Known Exploited Vulnerabilities catalog and shows no active community exploitation. Exploit code availability and active exploitation attempts have not been reported. The vulnerability remains on an inactive Hot List status, suggesting limited current threat activity or public disclosure intensity.