langchain-ai langchainjs up to 1.1.17 validateSafeUrl server-side request forgery

Summaryinfo

A vulnerability was found in langchain-ai langchainjs up to 1.1.17. It has been classified as critical. Impacted is the function validateSafeUrl. The manipulation leads to server-side request forgery. This vulnerability is documented as CVE-2026-27795. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in langchain-ai langchainjs up to 1.1.17 and classified as critical. This issue affects the function validateSafeUrl. The manipulation with an unknown input leads to a server-side request forgery vulnerability. Using CWE to declare the problem leads to CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-27795 since 02/24/2026. The exploitation is known to be easy. The attack may be initiated remotely. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 1.1.18 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 2812d2b2b9fd9343c4850e2ab906b8cf440975ee is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-8697). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Artificial Intelligence Software

Vendor

• langchain-ai

Name

• langchainjs

Version

• 1.1.0
• 1.1.1
• 1.1.2
• 1.1.3
• 1.1.4
• 1.1.5
• 1.1.6
• 1.1.7
• 1.1.8
• 1.1.9
• 1.1.10
• 1.1.11
• 1.1.12
• 1.1.13
• 1.1.14
• 1.1.15
• 1.1.16
• 1.1.17

License

• open-source

Website

• Product: https://github.com/langchain-ai/langchainjs/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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