picklescan missing detection by simple obfuscation of a builtins.eval call

Exploitation

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

CVSS 4.0

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

EPSS

• CVE-2026-53874: 0.52% estimated exploitation activity in the next 30 days; percentile 44.17 (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 An unsafe deserialization vulnerability allows any unauthenticated user to execute arbitrary code on the host loading a pickle payload from an untrusted source. Details It's possible to hide the eval call nested under another callable via getattr. PoC Impact Who is impacted? Any organization or individual relying on picklescan to detect malicious pickle files from untrusted sources. What is the impact? Attackers can embed malicious code in pickle file that remains undetected but executes when the pickle file is loaded. Supply Chain Attack: Attackers can distribute infected pickle files to system that load serialized ML models, APIs, or saved Python objects from untrusted sources.

Published by the source

2 Feb 2026, 20:45 UTC

Last modified by the source

7 Jul 2026, 17:56 UTC

Source last checked

26 Oct 2026, 13:45 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-9m3x-qqw2-h32h

2. Revision 2 · amended · 24 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-9m3x-qqw2-h32h

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# Patch Next advisory brief: CVE-2026-53874

Advisory: picklescan missing detection by simple obfuscation of a `builtins.eval` call
IDs: CVE-2026-53874, GHSA-9m3x-qqw2-h32h
Record: https://patchnext.com/advisories/cve-2026-53874 (revision 3, source checked 26 Oct 2026, 13:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: picklescan 1.0.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI picklescan: affected < 1.0.1; fixed in 1.0.1

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

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on picklescan.
- 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-9m3x-qqw2-h32h (OSV record GHSA-9m3x-qqw2-h32h lists affected ranges: PyPI picklescan >=0 <1.0.1 (fixed))
- Verified: https://github.com/advisories/GHSA-9m3x-qqw2-h32h (GitHub-reviewed advisory GHSA-9m3x-qqw2-h32h lists affected ranges: PyPI picklescan >=0 <1.0.1)

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