CVE-2026-27795

Описание

LangChain is a framework for building LLM-powered applications. Prior to version 1.1.8, a redirect-based Server-Side Request Forgery (SSRF) bypass exists in RecursiveUrlLoader in @langchain/community. The loader validates the initial URL but allows the underlying fetch to follow redirects automatically, which permits a transition from a safe public URL to an internal or metadata endpoint without revalidation. This is a bypass of the SSRF protections introduced in 1.1.14 (CVE-2026-26019). Users should upgrade to @langchain/community 1.1.18, which validates every redirect hop by disabling automatic redirects and re-validating Location targets before following them. In this version, automatic redirects are disabled (redirect: "manual"), each 3xx Location is resolved and validated with validateSafeUrl() before the next request, and a maximum redirect limit prevents infinite loops.

A flaw was found in @langchain/community. The RecursiveUrlLoader component, which is responsible for loading URLs, fails to revalidate URLs after following redirects. This allows an attacker to bypass existing Server-Side Request Forgery (SSRF) protections by initially providing a safe public URL that then redirects to an internal or sensitive metadata endpoint. This could lead to unauthorized information disclosure or access to internal network resources.