CVE-2026-33054 CRITICAL

CVE-2026-33054: Mesop: Path Traversal utilizing `FileStateSessionBackend` leads to Application Denial of Service and File Write/Deletion

Vendor Mesop-Dev
Product mesop
Weakness CWE-22 · Path traversal
Published March 20, 2026
Last update March 20, 2026

CVSS base score

10.0/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

What the vulnerability does

01Description

Mesop is a Python-based UI framework that allows users to build web applications. Versions 1.2.2 and below contain a Path Traversal vulnerability that allows any user supplying an untrusted state_token through the UI stream payload to arbitrarily target files on the disk under the standard file-based runtime backend. This can result in application denial of service (via crash loops when reading non-msgpack target files as configurations), or arbitrary file manipulation. This vulnerability heavily exposes systems hosted utilizing FileStateSessionBackend. Unauthorized malicious actors could interact with arbitrary payloads overwriting or explicitly removing underlying service resources natively outside the application bounds. This issue has been fixed in version 1.2.3.

Key dates

02Disclosure timeline

March 20, 2026 CVE published
March 20, 2026 Record updated