langchain-ai langchainjs up to 1.1.13 URL Validation String.startsWith server-side request forgery

Summaryinfo

A vulnerability categorized as critical has been discovered in langchain-ai langchainjs up to 1.1.13. Affected by this issue is the function String.startsWith of the component URL Validation Handler. The manipulation results in server-side request forgery. This vulnerability is cataloged as CVE-2026-26019. The attack may be launched remotely. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in langchain-ai langchainjs up to 1.1.13. Affected is the function String.startsWith of the component URL Validation Handler. The manipulation with an unknown input leads to a server-side request forgery vulnerability. CWE is classifying the issue as 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. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

LangChain is a framework for building LLM-powered applications. Prior to 1.1.14, the RecursiveUrlLoader class in @langchain/community is a web crawler that recursively follows links from a starting URL. Its preventOutside option (enabled by default) is intended to restrict crawling to the same site as the base URL. The implementation used String.startsWith() to compare URLs, which does not perform semantic URL validation. An attacker who controls content on a crawled page could include links to domains that share a string prefix with the target, causing the crawler to follow links to attacker-controlled or internal infrastructure. Additionally, the crawler performed no validation against private or reserved IP addresses. A crawled page could include links targeting cloud metadata services, localhost, or RFC 1918 addresses, and the crawler would fetch them without restriction. This vulnerability is fixed in 1.1.14.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-26019 since 02/09/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. Technical details are known, but there is no available exploit.

Upgrading to version 1.1.14 eliminates this vulnerability.

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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

Website

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

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