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GHSA-gf3v-fwqg-4vh7
No affected components available
Description
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 (e.g., https://example.com.attacker.com passes a startsWith check against https://example.com), 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 (169.254.169.254), localhost, or RFC 1918 addresses, and the crawler would fetch them without restriction.
Impact
An attacker who can influence the content of a page being crawled (e.g., by placing a link on a public-facing page, forum, or user-generated content) could cause the crawler to:
- Fetch cloud instance metadata (AWS, GCP, Azure), potentially exposing IAM credentials and session tokens
- Access internal services on private networks (
10.x,172.16.x,192.168.x) - Connect to localhost services
- Exfiltrate response data via attacker-controlled redirect chains
This is exploitable in any environment where RecursiveUrlLoader runs on infrastructure with access to cloud metadata or internal services — which includes most cloud-hosted deployments.
Resolution
Two changes were made:
-
Origin comparison replaced. The
startsWithcheck was replaced with a strict origin comparison using the URL API (new URL(link).origin === new URL(baseUrl).origin). This correctly validates scheme, hostname, and port as a unit, preventing subdomain-based bypasses. -
SSRF validation added to all fetch operations. A new URL validation module (
@langchain/core/utils/ssrf) was introduced and applied before every outbound fetch in the crawler. This blocks requests to:- Cloud metadata endpoints:
169.254.169.254,169.254.170.2,100.100.100.200,metadata.google.internal, and related hostnames - Private IP ranges:
10.0.0.0/8,172.16.0.0/12,192.168.0.0/16,127.0.0.0/8,169.254.0.0/16 - IPv6 equivalents:
::1,fc00::/7,fe80::/10 - Non-HTTP/HTTPS schemes (
file:,ftp:,javascript:, etc.)
- Cloud metadata endpoints:
Cloud metadata endpoints are unconditionally blocked and cannot be overridden.
Workarounds
Users who cannot upgrade immediately should avoid using RecursiveUrlLoader on untrusted or user-influenced content, or should run the crawler in a network environment without access to cloud metadata or internal services.
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. The attacker needs the user to perform some action, like clicking a link. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the confidentiality of the information.
Limited exploitation activity has been observed. Close monitoring and planned remediation are recommended.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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