An important security vulnerability has been identified in the langchain/community package, affecting versions up to 1.1.13. This Server-Side Request Forgery (SSRF) flaw, known as CVE-2026-26019, poses a moderate risk due to its potential to reveal sensitive data from cloud metadata and internal networks.
Understanding the Vulnerability
The issue arises from the RecursiveUrlLoader class, designed for recursive web crawling within the same domain. The vulnerability stemmed from the use of JavaScript’s String.startsWith() method for URL validation. This method’s non-semantic approach allowed crafted subdomains to bypass domain restrictions, thus exposing internal services.
Moreover, the flaw permitted access to private or reserved IP addresses, including cloud metadata endpoints like 169.254.169.254, localhost, and internal networks such as 10.x, 172.16.x, and 192.168.x. These oversights made it possible for attackers to exploit the vulnerability to access sensitive information.
Potential Impacts and Exploits
Attackers could leverage this flaw to compromise IAM credentials, tokens, or access internal service data in environments where LangChain operates with privileged network access. A malicious actor could insert harmful links into user-generated or publicly crawled content, allowing them to retrieve cloud metadata and credentials from platforms like AWS, GCP, or Azure. Additionally, they could probe internal APIs and services, potentially leading to data exfiltration through redirect chains.
The exploit requires minimal privileges and relies on the crawler fetching a manipulated page, making it a serious concern for affected systems.
Mitigation and Updates
LangChain has addressed this vulnerability in version 1.1.14 by implementing strict origin validation via the URL API and introducing new SSRF filters in @langchain/core/utils/ssrf. These updates ensure that requests to private, loopback, cloud metadata, and non-HTTP(S) schemes are effectively blocked.
Users unable to upgrade are advised to avoid running RecursiveUrlLoader on untrusted content and to isolate the component in environments that cannot access internal networks or metadata services.
Stay informed with the latest cybersecurity news by following us on Google News, LinkedIn, and X. For more insights or to share your stories, get in touch with us.
