Potential double free of buffer during string decoding

Exploitation

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

CVSS

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

EPSS

• CVE-2022-31117: 1.88% estimated exploitation activity in the next 30 days; percentile 79.43 (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.

Impact What kind of vulnerability is it? Who is impacted? When an error occurs while reallocating the buffer for string decoding, the buffer gets freed twice. Due to how UltraJSON uses the internal decoder, this double free is impossible to trigger from Python. Patches Has the problem been patched? What versions should users upgrade to? Users should upgrade to UltraJSON 5.4.0. Workarounds Is there a way for users to fix or remediate the vulnerability without upgrading? There is no workaround. For more information If you have any questions or comments about this advisory: Open an issue in UltraJSON

Published by the source

5 Jul 2022, 21:05 UTC

Last modified by the source

7 Jul 2026, 11:56 UTC

Source last checked

26 Oct 2026, 13:08 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-fm67-cv37-96ff

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-fm67-cv37-96ff

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# Patch Next advisory brief: CVE-2022-31117

Advisory: Potential double free of buffer during string decoding
IDs: CVE-2022-31117, GHSA-fm67-cv37-96ff
Record: https://patchnext.com/advisories/cve-2022-31117 (revision 2, source checked 26 Oct 2026, 13:08 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: ujson 5.4.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI ujson: affected < 5.4.0; fixed in 5.4.0

## Suggested inspection (read-only)
- `python -m pip show ujson`: 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 ujson.
- 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-fm67-cv37-96ff (OSV record GHSA-fm67-cv37-96ff lists affected ranges: PyPI ujson >=0 <5.4.0 (fixed))
- Verified: https://github.com/advisories/GHSA-fm67-cv37-96ff (GitHub-reviewed advisory GHSA-fm67-cv37-96ff lists affected ranges: PyPI ujson >=0 <5.4.0)

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