Lupa has a Sandbox escape and RCE due to incomplete attribute_filter enforcement in getattr / setattr

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

7.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H · score source

EPSS

• CVE-2026-34444: 0.64% estimated exploitation activity in the next 30 days; percentile 50.58 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The attributefilter in the Lupa library is intended to restrict access to sensitive Python attributes when exposing objects to Lua. However, the filter is not consistently applied when attributes are accessed through built-in functions like getattr and setattr. This allows an attacker to bypass the intended restrictions and eventually achieve arbitrary code execution. Details The attributefilter is meant to block access to attributes such as class, mro, and similar internal properties. In practice, it only applies to direct attribute access: - obj.attr → filtered - getattr(obj, "attr") → not filtered Because of this inconsistency, it’s possible to bypass the filter entirely, if access to the Python builtins is granted to Lua code. An attacker can use getattr to- - Access class - Walk the mro chain - Call subclasses() - Iterate over available classes - Find a function that exposes globals - Retrieve something like os.system At that point, arbitrary command execution becomes…

Published by the source

7 Apr 2026, 15:48 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:41 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-69v7-xpr6-6gjm

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-69v7-xpr6-6gjm

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# Patch Next advisory brief: CVE-2026-34444

Advisory: Lupa has a Sandbox escape and RCE due to incomplete attribute_filter enforcement in getattr / setattr
IDs: CVE-2026-34444, GHSA-69v7-xpr6-6gjm
Record: https://patchnext.com/advisories/cve-2026-34444 (revision 3, source checked 26 Oct 2026, 13:41 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI lupa: affected <= 2.6

## Suggested inspection (read-only)
- `python -m pip show lupa`: prints the installed version. Run with the environment that serves production active.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on lupa.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-69v7-xpr6-6gjm (OSV record GHSA-69v7-xpr6-6gjm lists affected ranges: PyPI lupa >=0 <=2.6)
- Verified: https://github.com/advisories/GHSA-69v7-xpr6-6gjm (GitHub-reviewed advisory GHSA-69v7-xpr6-6gjm lists affected ranges: PyPI lupa >=0 <=2.6)

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