CVE-2026-33057
CriticalExploitedPublic exploitMesop Affected by Unauthenticated Remote Code Execution via Test Suite Route /exec-py
Published Mar 18, 2026 · Updated Aug 12, 2026 · Also known as GHSA-gjgx-rvqr-6w6v, PYSEC-2026-412
Key Facts
Patch immediately- CVE-2026-33057 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Mesop (Mesop-Dev).
- It is exploited in the wild, listed in Industry KEV feed since Sep 26, 2026. Public exploit code is available.
- EPSS estimates a 4.1% probability of exploitation in the next 30 days.
- Fixed versions are available, including Mesop 1.2.3.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
4.1%
Higher than 90.6% of all scored CVEs
Exploited in the wild
Yes
1 catalog listing
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2026-33057 brief as a PDF
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Description
Mesop is a Python-based UI framework that allows users to build web applications. In versions 1.2.2 and below, an explicit web endpoint inside the ai/ testing module infrastructure directly ingests untrusted Python code strings unconditionally without authentication measures, yielding standard Unrestricted Remote Code Execution. Any individual capable of routing HTTP logic to this server block will gain explicit host-machine command rights. The AI codebase package includes a lightweight debugging Flask server inside ai/sandbox/wsgi_app.py. The /exec-py route accepts base_64 encoded raw string payloads inside the code parameter natively evaluated by a basic POST web request. It saves it rapidly to the operating system logic path and injects it recursively using execute_module(module_path...). This issue has been fixed in version 1.2.3.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| Industry KEV feed | Sep 26, 2026 | n/a | Not reported |
Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Affected Products
3 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| MesopMesop-Dev | >= < 1.2.3 | 1.2.3 |
Patched Releases
Mesop
1.2.3
Timeline
Publicly disclosed
Mar 18, 2026
Last updated
Aug 12, 2026
Added to Industry KEV feed
Sep 26, 2026
Weakness Type
- CWE-94 Improper Control of Generation of Code ('Code Injection')
References
- advisoryGHSA advisory
- advisoryhttps://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33057.json
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2026-33057
- articlehttps://github.com/mesop-dev/mesop/commit/825f55970c20686de3f28e2c66df4d74e9d4db47
- articlehttps://github.com/mesop-dev/mesop/security/advisories/GHSA-gjgx-rvqr-6w6v
FAQ
Common Questions.
Mesop is a Python-based UI framework that allows users to build web applications.
Affected: Mesop (Mesop-Dev) versions >= < 1.2.3. The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed since Sep 26, 2026.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including Mesop 1.2.3.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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