Path Traversal in Mesop-Dev Mesop
CVE-2026-33054
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.
Vulnerability class: Path Traversal (Directory Traversal)
EPSS: 0.007 (49.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.
Affected products
- Mesop-dev Mesop — versions < 1.2.3
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC, Release Notes)
Frequently asked questions
- What is CVE-2026-33054?
- CVE-2026-33054 is a critical-severity vulnerability in Mesop-Dev Mesop, classified under Path Traversal. CVSS score: 10.0/10. Published 2026-03-20.
- How severe is CVE-2026-33054?
- Critical severity. CVSS v3 base score is 10.0 out of 10.