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Vulnerability Analysis
Mesop: Path Traversal utilizing `FileStateSessionBackend` leads to Application Denial of Service and File Write/Deletion

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.

No Active Exploit Signals
CVSS Base Score
10.0
CRITICAL
Exploitability:3.9
Impact Score:6.1
Temporal Score:-
EPSS:0.71%

Threat Intelligence Signals

CISA KEV
No
KEV Date Added
Ransomware Use
KEV Due Date
VulnCheck In-the-Wild
No
Nuclei Template
No
EPSS Score
0.713%
EPSS Percentile
48.8th pct
GitHub Severity
CRITICAL
SSVC Exploitation
SSVC Automatable
Vulnerability Class

Identity & Timeline

Status-
Assigning Authority-
CVSS Version / Source-
Reserved-
Published-
Patch Date (date_public)-
Exploit DB Date-
First GitHub PoC Date-
Last Updated-
Time to Patch (Days to fix)-
Exploit Release Gap-
PoC Release Gap-
Exploit DB ReferencesNone identified

Affected Products & Versions

Vendor Product Affected Versions
No affected products specified.

References

No reference links found.

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