CVE-2022-31116: Fedoraproject Fedora

High severity, CVSS 7.5. EPSS: 2.5% chance of exploitation in the next 30 days.

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.

Affected products

• Fedoraproject Fedora: version 35 only; version 36 only
• Ultrajson Project Ultrajson: before 5.4.0 (fixed in 5.4.0)

Published 2022-07-05. Last modified 2026-06-17.