CVE-2022-31116highCWE-670

CVE-2022-31116: high-severity vulnerability in ultrajson

Incorrect handling of invalid surrogate pair characters in ujson

Published · Updated

Follow this CVE+ Monitor ultrajson+ Monitor ujson

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 7.5epss 2.5%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
ultrajson · ultrajson
Related CVEs — ultrajson

In the same product, most dangerous first.

CVE-2022-31117MEDIUMDouble free of buffer during string decoding in ujsonEPSS 1.9%CVE-2026-32874HIGHUltraJSON has a Memory Leak parsing large integers allows DoSEPSS 0.5%CVE-2026-32875HIGHUltraJSON has an integer overflow handling large indent leads to buffer overflow or infinite loopEPSS 0.5%CVE-2026-44660HIGHUltraJSON: Memory Leak in ujson.dump() on Write FailureEPSS 0.4%CVE-2026-54911MEDIUMUltraJSON: Malformed/Truncated UTF-8 Accepted and Silently Rewritten in ujson.dumps()EPSS 0.4%