CVE-2022-31116 | Incorrect handling of invalid surrogate pair characters in ujson

Exp

UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Affected versions were found to improperly decode certain characters. JSON strings that contain escaped surrogate characters not part of a proper surrogate pair were decoded incorrectly. Besides corrupting strings, this allowed for potential key confusion and value overwriting in dictionaries. All users parsing JSON from untrusted sources are vulnerable. From version 5.4.0, UltraJSON decodes lone surrogates in the same way as the standard library's `json` module does, preserving them in the parsed output. Users are advised to upgrade. There are no known workarounds for this issue.

Published: 2022-07-05 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2022-31116 is rated High Exploit Risk (73.8/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.28%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

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

Public exploit references (Exploit-DB) for CVE-2022-31116

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2022-31116

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 2026-07-02 1.83% 2.28% +0.45%
2 2026-06-15 0.07% 1.83% +1.76%
3 2026-01-14 — 0.07% —

Full EPSS history (14 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2022-31116

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/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:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
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.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/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:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
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.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/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:L)
Exploitation conditions are straightforward and predictable.
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.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2022-31116

GitHub Security Advisory for CVE-2022-31116

GHSA-wpqr-jcpx-745r · Severity: high · Ecosystem: pip — Incorrect handling of invalid surrogate pair characters

OS Trackers for CVE-2022-31116

vendor priority summary link
alpine high CVE-2022-31116: 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-2022-31116
debian not yet assigned CVE-2022-31116 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-2022-31116
gentoo normal CVE-2022-31116: 1 GLSA(s) (202403-03), 1 atom(s) (dev-python/ujson); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2022-31116
redhat medium — https://access.redhat.com/security/cve/CVE-2022-31116
suse medium CVE-2022-31116 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-2022-31116/
ubuntu medium CVE-2022-31116 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): needs-triage 11, ignored 10, DNE 8, not-affected 7, released 5, needed 1. https://ubuntu.com/security/CVE-2022-31116

Affected software / configurations for CVE-2022-31116

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-2022-31116

cvelogic Threat Intelligence