CVE-2026-51884

Deferred Deferred - Pending Action

BaseFortify

Publication date: 2026-10-01

Last updated on: 2026-10-05

Assigner: MITRE

Description

The /knowledge_base/upload_temp_docs temporary document upload endpoint in Langchain Chatchat 0.3.1 is vulnerable to path traversal. By crafting malicious filenames, an attacker can write files to arbitrary locations on the server, bypassing the intended restrictions on the temporary directory.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-10-01

Last Modified

2026-10-05

Generated

2026-10-19

AI Q&A

2026-10-02

EPSS Evaluated

2026-10-18

NVD

CVE-2026-51884

EUVD

EUVD-2026-91121

Affected Vendors & Products

Vendor	Product	Version / Range
n/a	n/a	n/a

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-22	The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Attack-Flow Graph

Executive Summary

This vulnerability is a path traversal issue in the /knowledge_base/upload_temp_docs endpoint of Langchain Chatchat version 0.3.1. It allows attackers to write files to arbitrary locations on the server by crafting malicious filenames, bypassing restrictions meant for the temporary directory.

Detection Guidance

To detect this vulnerability, inspect file uploads to the /knowledge_base/upload_temp_docs endpoint. Check for filenames containing path traversal sequences like ../ or absolute paths. Monitor server file system for unexpected file writes outside the intended temporary directory.

Impact Analysis

An attacker could exploit this to overwrite critical system files, inject malicious code, or gain unauthorized access to sensitive data stored on the server. This could lead to system compromise or data breaches.

Compliance Impact

This vulnerability could lead to unauthorized data access or modification, violating GDPR's data protection requirements or HIPAA's safeguards for protected health information. Compliance violations may result in legal penalties or reputational damage.

Mitigation Strategies

Immediately upgrade Langchain Chatchat to a patched version if available. If not, disable the /knowledge_base/upload_temp_docs endpoint or restrict file upload functionality. Monitor server file system for unauthorized file writes in temporary directories.

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