CVE-2025-6985: langchain-ai langchain-ai/langchain

Vulnerability summary

CVE-2025-6985 is a high (CVSS 7.5) vulnerability in langchain-ai langchain-ai/langchain. EPSS estimates a 0.51% chance of exploitation in the next 30 days, higher than 42.1% of scored vulnerabilities.

Timeline

1. 06-10-2025
   PublishedVulnerability first disclosed.
2. 06-10-2025
   Last modifiedVulnerability information updated.

Description

The HTMLSectionSplitter class in langchain-text-splitters version 0.3.8 is vulnerable to XML External Entity (XXE) attacks due to unsafe XSLT parsing. This vulnerability arises because the class allows the use of arbitrary XSLT stylesheets, which are parsed using lxml.etree.parse() and lxml.etree.XSLT() without any hardening measures. In lxml versions up to 4.9.x, external entities are resolved by default, allowing attackers to read arbitrary local files or perform outbound HTTP(S) fetches. In lxml versions 5.0 and above, while entity expansion is disabled, the XSLT document() function can still read any URI unless XSLTAccessControl is applied. This vulnerability allows remote attackers to gain read-only access to any file the LangChain process can reach, including sensitive files such as SSH keys, environment files, source code, or cloud metadata. No authentication, special privileges, or user interaction are required, and the issue is exploitable in default deployments that enable custom XSLT.

• CWE-611Improper Restriction of XML External Entity ReferenceThe product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.