PySyft server-side arbitrary Python execution after code approval

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-2026-31220: 0.63% estimated exploitation activity in the next 30 days; percentile 50.32 (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.

PySyft (Syft Datasite/Server) versions 0.9.5 and earlier are vulnerable to remote code execution due to insufficient validation and sandboxing of user-submitted code. The system allows low-privileged users to submit Python functions (via @sy.syftfunction()) for remote execution on the server. While a code approval mechanism exists, the submitted code undergoes no security checks for dangerous operations (e.g., file access, command execution). Once approved, the code is executed within the server process using exec() and eval() functions without proper isolation. A remote attacker can leverage this to execute arbitrary Python code on the server, leading to complete compromise of the server environment.

Published by the source

12 May 2026, 18:30 UTC

Last modified by the source

29 Jun 2026, 12:26 UTC

Source last checked

26 Oct 2026, 13:41 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-cfpg-c974-jfhq

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-cfpg-c974-jfhq

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-cfpg-c974-jfhq

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# Patch Next advisory brief: CVE-2026-31220

Advisory: PySyft server-side arbitrary Python execution after code approval
IDs: CVE-2026-31220, GHSA-cfpg-c974-jfhq
Record: https://patchnext.com/advisories/cve-2026-31220 (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: 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 syft: affected <= 0.9.5

## Suggested inspection (read-only)
- `python -m pip show syft`: 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 syft.
- 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-cfpg-c974-jfhq (GitHub-reviewed advisory GHSA-cfpg-c974-jfhq lists affected ranges: PyPI syft >=0 <=0.9.5)
- Verified: https://osv.dev/vulnerability/GHSA-cfpg-c974-jfhq (OSV record GHSA-cfpg-c974-jfhq lists affected ranges: PyPI syft >=0 <=0.9.5)

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