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Vulnerability · Published Feb 25, 2026 · Assigned by GitHub_M

CVE-2026-27795LangChain Community: redirect chaining can lead to SSRF bypass via RecursiveUrlLoader

Medium 4.1

In plain English

A medium-severity server-side request forgery in langchainjs from langchain-ai. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 16% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)4.1Medium
Exploit odds (30 days)0.2%top 83.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
npm@langchain/community1.1.18GHSA-mphv-75cg-56wg

Affected products (as reported)

VendorProductVersions
langchain-ai langchainjs < 1.1.18

Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N

References