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HIGH

XXE Vulnerability in langchain-ai/langchain

Published Oct 6, 2025

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.

Affected products

Remediation

Red Hat mitigation

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Weaknesses (1)

CWE-611

XXE

References (8)

Change history (0)

No recorded changes yet.

Sources
CVE.org / MITRE
Status PUBLISHED
Assigner @huntr_ai
Published Oct 6, 2025
Updated Oct 6, 2025
Reserved Jul 1, 2025
Link CVE-2025-6985
CISA Vulnrichment
Updated Oct 6, 2025
NVD
Status Deferred
Modified Jun 17, 2026
Link CVE-2025-6985
Red Hat
Severity Important
Public date Oct 6, 2025
Links CVE-2025-6985 - Bugzilla
GHSA-M42M-M8CR-8M58