Vulnerability · Published Oct 6, 2025 · Assigned by @huntr_ai
CVE-2025-6985XXE Vulnerability in langchain-ai/langchain
High 7.5
In plain English
A high-severity XML external entity in langchain-ai/langchain from langchain-ai. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | langchain-text-splitters | 0.3.9 | GHSA-m42m-m8cr-8m58 |
| PyPI | langchain-text-splitters | 0.3.9 | PYSEC-2026-1520 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| langchain-ai | langchain-ai/langchain | unspecified – through latest |
Weakness: CWE-611 · Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N