CVE-2026-27641: JUGMAC00 Flask-Reuploaded

Critical severity, CVSS 9.8. EPSS: 1.2% chance of exploitation in the next 30 days.

Flask-Reuploaded provides file uploads for Flask. A critical path traversal and extension bypass vulnerability in versions prior to 1.5.0 allows remote attackers to achieve arbitrary file write and remote code execution through Server-Side Template Injection (SSTI). Flask-Reuploaded has been patched in version 1.5.0. Some workarounds are available. Do not pass user input to the `name` parameter, use auto-generated filenames only, and implement strict input validation if `name` must be used.

Affected products

• JUGMAC00 Flask-Reuploaded: before 1.5.0 (fixed in 1.5.0)

Published 2026-02-25. Last modified 2026-06-17.