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RewindexCVEsLangChain (LangSmith)

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

Medium · CVSS 4.1 (CVSS 3.1)EPSS 0.25%, 16th percentilePublished Updated Assigner: GitHub_M

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.

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

Tracked companies

LangChain (LangSmith)

Mapped from the CVE’s affected-product data, NVD CPE matches, vendor advisories or package feeds. A mapping means the vendor’s software is named, not that its hosted service was exposed.

Status incidents that name it

No tracked status incident names this CVE.

Affected vendors and products

langchain-ai: langchainjs

References

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