# CVE-2026-54567

## Summary

- **CVE ID:** CVE-2026-54567
- **Severity:** HIGH
- **CVSS Score:** 7.5 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** CWE-178, CWE-434
- **Published:** Sep 14, 2026
- **Last Modified:** Sep 16, 2026

## Description

Flask-Reuploaded provides file uploads for Flask. From 1.5.0 until 1.6.0, UploadSet.save(storage, name=...) in src/flask_uploads/flask_uploads.py applies lowercase_ext to the default upload path but uses the case-preserving extension helper for a caller-supplied name before extension_allowed evaluates an AllExcept denylist. An attacker who controls the name override can use a mixed-case dangerous extension to bypass a lowercase denylist and store the file in the served upload directory. Exploitation requires a denylist configuration, a user-influenced name override, and a deployment that resolves or executes extensions case-insensitively; pure allowlists remain protected and path containment is not bypassed. On an execution-capable upload directory, the stored file can execute with the web server's privileges and affect confidentiality, integrity, and availability. This issue is fixed in version 1.6.0.

## Affected Products

- jugmac00 — flask-reuploaded (< 1.6.0)

## References

- [CNA](https://github.com/jugmac00/flask-reuploaded/security/advisories/GHSA-937x-gpqr-72gg)
- [CNA](https://github.com/jugmac00/flask-reuploaded/pull/186)
- [CNA](https://github.com/jugmac00/flask-reuploaded/commit/5ded76092429c6eb8a4af941b14fbde40a38fff4)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.58%
- **EPSS Percentile:** 46.4

---
_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._