CVE-2022-31117 | Double free of buffer during string decoding in ujson

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.

Published: 2022-07-05 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2022-31117 is rated Moderate Risk (48.8/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.39%). EPSS rose +1.22% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2022-31117

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.16% 1.39% +1.22%
2 2025-12-12 0.14% 0.16% +0.02%
3 2025-11-23 — 0.14% —

Full EPSS history (15 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2022-31117

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 3.6 [email protected]
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2022-31117

GitHub Security Advisory for CVE-2022-31117

GHSA-fm67-cv37-96ff · Severity: medium · Ecosystem: pip — Potential double free of buffer during string decoding

OS Trackers for CVE-2022-31117

vendor priority summary link
alpine medium CVE-2022-31117: 1 source package rows (py3-ujson); 7 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 7, open 0. https://security.alpinelinux.org/vuln/CVE-2022-31117
debian not yet assigned CVE-2022-31117 not yet assigned priority: Debian including 1 source packages (ujson), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 4, open 1. https://security-tracker.debian.org/tracker/CVE-2022-31117
gentoo normal CVE-2022-31117: 1 GLSA(s) (202403-03), 1 atom(s) (dev-python/ujson); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2022-31117
redhat medium — https://access.redhat.com/security/cve/CVE-2022-31117
suse medium CVE-2022-31117 severity moderate: SUSE including 10 source package names (python-ujson, python2-ujson-1.35-150100.3.5.1, …), 29 product×package rows across 23 product lines (HPE Helion OpenStack 8, SUSE Linux Enterprise Module for Development Tools 15 SP3, … (23 product lines)): Fixed 24, Will Not Fix 5. https://www.suse.com/security/cve/CVE-2022-31117/
ubuntu medium CVE-2022-31117 medium priority: Ubuntu including 3 source packages (collada2gltf, pandas, ujson), 42 status rows across 14 suites (bionic, focal, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 11, needs-triage 11, DNE 8, not-affected 6, released 5, needed 1. https://ubuntu.com/security/CVE-2022-31117

Affected software / configurations for CVE-2022-31117

Vendor Product Version Raw CPE
ultrajson_project ultrajson < 5.4.0 cpe:2.3:a:ultrajson_project:ultrajson:*:*:*:*:*:python:*:*
fedoraproject fedora 35 cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
fedoraproject fedora 36 cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:*

References for CVE-2022-31117

cvelogic Threat Intelligence