CVE-2026-27795
CVE-2026-27795 · LangChain Community: redirect chaining can lead to SSRF bypass via RecursiveUrlLoader
This page contains facts from public vulnerability sources. Check the original advisory before updating.
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.
CVSS 4.1 · Medium · EPSS 0.2% · Fix available
- Published
- Updated
Stack: node
Affected products and versions
langchainjs
- Versions
- < 1.1.18: Affected
No fix published
@langchain/community npm
- Affected ranges
- SEMVER: < 1.1.18
Update to 1.1.18
Original sources
- https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-mphv-75cg-56wg
- https://github.com/langchain-ai/langchainjs/security/advisories/GHSA-gf3v-fwqg-4vh7
- https://github.com/langchain-ai/langchainjs/pull/9990
- https://github.com/langchain-ai/langchainjs/commit/2812d2b2b9fd9343c4850e2ab906b8cf440975ee
- https://github.com/langchain-ai/langchainjs/commit/d5e3db0d01ab321ec70a875805b2f74aefdadf9d
- https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.14
- https://github.com/langchain-ai/langchainjs/releases/tag/%40langchain%2Fcommunity%401.1.18
- https://nvd.nist.gov/vuln/detail/CVE-2026-27795