APScheduler's JSONSerializer and CBORSerializer are vulnerable to Remote Code Execution (RCE) via Insecure Deserialization

Exploitation

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

CVSS

9.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

• CVE-2026-31072: 0.81% estimated exploitation activity in the next 30 days; percentile 56.95 (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.

The JSONSerializer and CBORSerializer in APScheduler (all versions including 3.10.x and 4.0.0a5) are vulnerable to Remote Code Execution (RCE) via Insecure Deserialization. The unmarshal_object function allows for arbitrary class instantiation and state injection by dynamically importing modules and calling setstate on any class available in the Python environment. An attacker can exploit this by submitting a specially crafted JSON or CBOR payload to an application using these serializers

Published by the source

19 May 2026, 18:32 UTC

Last modified by the source

27 Oct 2026, 16:15 UTC

Source last checked

28 Oct 2026, 06:10 UTC

1. Revision 5 · amended · 28 Oct 2026

   Amended from osv record GHSA-9cfw-f3f9-7mm7

2. Revision 4 · amended · 27 Oct 2026

   Amended from ghsa record GHSA-9cfw-f3f9-7mm7

3. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-9cfw-f3f9-7mm7

4. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-9cfw-f3f9-7mm7

5. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-9cfw-f3f9-7mm7

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# Patch Next advisory brief: CVE-2026-31072

Advisory: APScheduler's JSONSerializer and CBORSerializer are vulnerable to Remote Code Execution (RCE) via Insecure Deserialization
IDs: CVE-2026-31072, GHSA-9cfw-f3f9-7mm7
Record: https://patchnext.com/advisories/cve-2026-31072 (revision 5, source checked 28 Oct 2026, 06:10 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.8)
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 apscheduler: affected >= 4.0.0a1, <= 4.0.0a6

## Suggested inspection (read-only)
- `python -m pip show apscheduler`: 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 apscheduler.
- 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://github.com/advisories/GHSA-9cfw-f3f9-7mm7 (GitHub-reviewed advisory GHSA-9cfw-f3f9-7mm7 lists affected ranges: PyPI apscheduler >=4.0.0a1 <=4.0.0a6)
- Verified: https://osv.dev/vulnerability/GHSA-9cfw-f3f9-7mm7 (OSV record GHSA-9cfw-f3f9-7mm7 lists affected ranges: PyPI apscheduler >=4.0.0a1 <=4.0.0a6)

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