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TI-2026-25497 Aliases CVE-2026-33054GHSA-8qvf-mr4w-9x2c

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

Priority HIGH 82CWE-22Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00741 54th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed mesop (mesop-dev): 1.2.3mesop (PyPI): 1.2.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
mesop-devmesopbefore 1.2.31.2.3Patch availableCNA
—mesop (PyPI)before 1.2.31.2.3Patch availableGHSA-8qvf-mr4w-9x2c
  • mesop Vendormesop-dev Affected before 1.2.3 Fixed in 1.2.3 Patch available CNA
  • mesop (PyPI) Vendor— Affected before 1.2.3 Fixed in 1.2.3 Patch available GHSA-8qvf-mr4w-9x2c

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:mesop-dev:mesop:*:*:*:*:*:*:*:*before 1.2.3Vulnerablemesop-dev
  • cpe:2.3:a:mesop-dev:mesop:*:*:*:*:*:*:*:* Versions before 1.2.3 Vulnerable ·mesop-dev

Remediation

  • Fix · CNA mesop (mesop-dev) Fixed in 1.2.3
  • Fix · GHSA-8qvf-mr4w-9x2c mesop (PyPI) Fixed in 1.2.3 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-33054
  2. 2026-10-03 Alias added: GHSA-8qvf-mr4w-9x2c

References

Exploit 1

Patch 1

Advisory 1

Other 2

  • TI-2026-25500 Mesop Affected by Unauthenticated Remote Code Execution via Test Suite Route /exec-py CVSS 3.1CRITICAL 9.8
  • TI-2026-27068 Mesop: Unbounded Thread Creation in WebSocket Handler Leads to Denial of Service CVSS 3.1HIGH 7.5

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences