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

> Attackers can corrupt strings and overwrite dictionary values by sending JSON with invalid surrogate pairs to applications using UltraJSON.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 Jul 2022
- **Updated:** 22 Apr 2025
- **Also known as:** DEBIAN-CVE-2022-31116, GHSA-wpqr-jcpx-745r, PYSEC-2026-1057, UBUNTU-CVE-2022-31116

## What is CVE-2022-31116?

CVE-2022-31116 is a high-severity vulnerability in Fedoraproject Fedora, published on 5 Jul 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-670 (Always-Incorrect Control Flow Implementation)

## Which versions are affected by CVE-2022-31116?

3 open source packages ship an affected version, including ujson. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ujson` | PyPI | All versions | 5.4.0 |
| `ujson` | PyPI | All versions | 5.4.0 |
| `ujson` | PyPI | All versions | 5.4.0 |

Products: Fedoraproject Fedora, Ultrajson Project Ultrajson.

## How do I fix CVE-2022-31116?

Upgrade ujson to 5.4.0 or later.

## Is CVE-2022-31116 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2022-31116 exists.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-31116 and fix it if it is affected.

What it is: CVE-2022-31116 is a high-severity vulnerability in Fedoraproject Fedora, published on 5 Jul 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2022-31116 exists.

Affected packages and fixed versions:
- ujson (PyPI): affected all versions; fixed in 5.4.0
- ujson (PyPI): affected all versions; fixed in 5.4.0
- ujson (PyPI): affected all versions; fixed in 5.4.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2022-31116/ (Markdown: https://insights.sbomify.com/CVE-2022-31116/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-31116
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-31116
- OSV: https://osv.dev/vulnerability/CVE-2022-31116

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-31116/
Summaries are generated and may contain mistakes; the official description above is the record.