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Fencer Vulns
medium 5.9

CVE-2022-31117 json

Double free of buffer during string decoding in ujson

published 2022-07-05 4 y ago modified 2026-07-07 4 mo ago also GHSA-fm67-cv37-96ff , PYSEC-2026-1056 , EUVD-2022-6334

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.9%
EPSS 1.9% chance of exploitation in 30 days, percentile 79%
public exploits
0
none known

Summary

UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. In versions prior to 5.4.0 an error occurring while reallocating a buffer for string decoding can cause the buffer to get freed twice. Due to how UltraJSON uses the internal decoder, this double free is impossible to trigger from Python. This issue has been resolved in version 5.4.0 and all users should upgrade to UltraJSON 5.4.0. There are no known workarounds for this issue.

Patch / fix

  • pypi ujson 5.4.0
  • ultrajson_project ultrajson 5.4.0
  • ujson Debian 14, Debian 13, Debian 12 5.4.0-1

debian advisories DEBIAN-CVE-2022-31117

  • ujson Ubuntu Pro 16.04 LTS 1.33-1ubuntu0.1~esm2
  • ujson Ubuntu Pro 18.04 LTS 1.35-2ubuntu0.1~esm1
  • ujson Ubuntu Pro 22.04 LTS 5.1.0-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2022-31117

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • python-ujson openstack 16.2, openstack 16.1 2.0.3-3.el8ost
  • python3-ujson openstack 16.2, openstack 16.1 2.0.3-3.el8ost

red hat advisories RHSA-2022:8864RHSA-2022:8850

  • python-ujson SLE Module for Package Hub 15 SP4, SLE Module for Package Hub 15 SP3, SLE Module for Development Tools 15 SP4 +3 more 1.35-150100.3.5.1

suse advisories SUSE-SU-2022:2673-1

  • python-ujson openSUSE Tumbleweed 5.10.0-1.5

opensuse advisories openSUSE-SU-2025:15107-1

  • py3-ujson Alpine 3.24, Alpine 3.23, Alpine 3.22 +6 more 5.4.0-r0

alpine advisories ALPINE-CVE-2022-31117

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2022-31117 updated cvss 5.9

python-ujson: Potential double free of buffer during string decoding

  • Red Hat OpenStack Platform 13 (Queens) python-ujson
    affected: no fix planned “Out of support scope”
  • Red Hat OpenStack Platform 16.1 python-ujson 2.0.3-3.el8ost, python3-ujson 2.0.3-3.el8ost
    fixed: vendor fix RHSA-2022:8864
  • Red Hat OpenStack Platform 16.2 python-ujson 2.0.3-3.el8ost, python3-ujson 2.0.3-3.el8ost
    fixed: vendor fix RHSA-2022:8850

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
18 mo ago

Exploit prediction

1.88% chance of exploitation in the next 30 days, higher than 79% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P
GitHub 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi ujson
<5.4.0
5.4.0

Affected products

  • ultrajson ultrajson

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.