CVE-2025-6985

Description

The HTMLSectionSplitter class in langchain-text-splitters 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.

How to fix CVE-2025-6985

To remediate CVE-2025-6985, upgrade the affected package to a fixed version below.

• —upgrade to 0.3.9 or later

Is CVE-2025-6985 being exploited?

Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.

Affected packages (1)

• from 0, < 0.3.9

CVSS scores

References (5)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2025-6985
• PATCHgithub.com/langchain-ai/langchain
• WEBgithub.com/langchain-ai/langchain/commit/43eef435505a1c907227b724c0c760ad5fc01790
• WEBgithub.com/langchain-ai/langchain/pull/31819