How severe is CVE-2022-31116?

CVE-2022-31116 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2022-31116?

CVE-2022-31116 affects the following packages: ujson (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2022-31116?

Update ujson to 5.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-31116 is resolved across your whole dependency graph.

How do I detect CVE-2022-31116 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ujson, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2022-31116 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2022-31116 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2022-31116, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2022-31116?

CVE-2022-31116 has an EPSS (Exploit Prediction Scoring System) score of 2.5%, placing it in the 85th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2022-31116?

CVE-2022-31116 is classified as CWE-670 (CWE-670). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2022-31116 published, and has it been updated?

CVE-2022-31116 was published on July 5, 2022 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

HIGH severity

CVE-2022-31116 — ujson

HIGHFix: ultrajson/ultrajson@67ec071

CVE-2022-31116 is a high-severity (CVSS 7.5) CWE-670 vulnerability in ujson. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for ujson — see the affected versions and patch details below.

Incorrect handling of invalid surrogate pair characters in ujson

Also known asGHSA-wpqr-jcpx-745rPYSEC-2026-1057

Published

Jul 5, 2022

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for CVE-2022-31116.

EPSS Exploitation Probability

via FIRST.org ↗

2.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs85th percentile — riskier than 85% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐍ujson

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Impact

What kind of vulnerability is it? Who is impacted?

Anyone parsing JSON from an untrusted source is vulnerable.

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.

Examples:

# An unpaired high surrogate character is ignored.
>>> ujson.loads(r'"\uD800"')
''
>>> ujson.loads(r'"\uD800hello"')
'hello'

# An unpaired low surrogate character is preserved.
>>> ujson.loads(r'"\uDC00"')
'\udc00'

# A pair of surrogates with additional non surrogate characters pair up in spite of being invalid.
>>> ujson.loads(r'"\uD800foo bar\uDC00"')
'foo bar𐀀'

Patches

Has the problem been patched? What versions should users upgrade to?

Users should upgrade to UltraJSON 5.4.0.

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:

>>> ujson.loads(r'"\uD800"')
'\ud800'
>>> ujson.loads(r'"\uD800hello"')
'\ud800hello'
>>> ujson.loads(r'"\uDC00"')
'\udc00'
>>> ujson.loads(r'"\uD800foo bar\uDC00"')
'\ud800foo bar\udc00'

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?

Short of switching to an entirely different JSON library, there are no safe alternatives to upgrading.

For more information

If you have any questions or comments about this advisory:

Open an issue in UltraJSON

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`ujson`	all versions	5.4.0`pip install --upgrade 'ujson==5.4.0'`

Affected Products

2 products · 3 configurations

fedorafedoraproject

2 versions

3536

Application

ultrajsonultrajson_project

< 5.4.0

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

UltraJSON is a fast JSON encoder and decoder written in pure C with bind…

github.comNVDJul 2022

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ujson, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ujson to 5.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-31116 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Product	Fixed in	Advisory
Red Hat OpenStack Platform 16.1	`python-ujson-0:2.0.3-3.el8ost`	RHSA-2022:8864
Red Hat OpenStack Platform 16.2	`python-ujson-0:2.0.3-3.el8ost`	RHSA-2022:8850

Frequently Asked Questions

### Impact _What kind of vulnerability is it? Who is impacted?_ Anyone parsing JSON from an untrusted source is vulnerable. 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. Examples: ```python # An unpaired high surrogate character is ignored. >>> ujson.loads(r'"\uD800"') '' >>> ujson.loads(r'"\uD800hello"') 'hello' # An unpaired low surrogate character is preserved. >>> ujson.loads(r'"\uDC00"') '\udc00' # A pair o