CVE-2026-24486: fastapiexpert python-multipart Path Traversal

Vulnerability summary

CVE-2026-24486 is a high (CVSS 8.6) Path Traversal vulnerability in fastapiexpert python-multipart. EPSS estimates a 2.24% chance of exploitation in the next 30 days, higher than 82.5% of scored vulnerabilities. 2 public exploits are recorded.

Timeline

1. 27-01-2026
   PublishedVulnerability first disclosed.
2. 16-09-2026
   Last modifiedVulnerability information updated.

Description

Python-Multipart is a streaming multipart parser for Python. Prior to version 0.0.22, a Path Traversal vulnerability exists when using non-default configuration options `UPLOAD_DIR` and `UPLOAD_KEEP_FILENAME=True`. An attacker can write uploaded files to arbitrary locations on the filesystem by crafting a malicious filename. Users should upgrade to version 0.0.22 to receive a patch or, as a workaround, avoid using `UPLOAD_KEEP_FILENAME=True` in project configurations.

• CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')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.