XXE in Langchain-Ai Langchain-Ai/langchain
CVE-2025-6985
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.
Vulnerability class: XXE (XML External Entity)
EPSS: 0.006 (45.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
Affected products
- Langchain-ai Langchain-ai/langchain — versions unspecified
Weakness classification (CWE)
Public proof-of-concept exploits
References
Frequently asked questions
- What is CVE-2025-6985?
- CVE-2025-6985 is a high-severity vulnerability in Langchain-Ai Langchain-Ai/langchain, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 7.5/10. Published 2025-10-06.
- How severe is CVE-2025-6985?
- High severity. CVSS v3 base score is 7.5 out of 10.
- Is CVE-2025-6985 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.