A GitHub advisory reports that the patch for an earlier SSRF issue (CVE-2026-39885) in mcp-from-openapi 2.3.0 can be bypassed, letting untrusted OpenAPI specs loaded by FrontMCP 1.2.1 trigger backend-origin requests to loopback or private services via DNS-to-loopback names, redirects, and IPv4-mapped IPv6 forms. In hosted or multi-user FrontMCP deployments where users can import specs, this can expose internal APIs not reachable externally.
Disclosed 11 September 2026 · Record updated 13 September 2026
Server-side request forgery from FrontMCP backends during OpenAPI tool generation, potentially exposing internal admin APIs, metadata-like services and other internal network endpoints; demonstrated with a local proof-of-concept canary.
VulnerabilitiesA GitHub advisory published on 11 September 2026 says the fix for an earlier server-side request forgery flaw in mcp-from-openapi still lets untrusted specs reach loopback services.
13 Sept 2026
