Memory Leak Affecting ujson package, versions *


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.07% (21st percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-UJSON-15757709
  • published23 Mar 2026
  • disclosed20 Mar 2026

Introduced: 20 Mar 2026

NewCVE-2026-32874  (opens in a new tab)
CWE-401  (opens in a new tab)

How to fix?

There is no fixed version for Debian:unstable ujson.

NVD Description

Note: Versions mentioned in the description apply only to the upstream ujson package and not the ujson package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Versions 5.4.0 through 5.11.0 contain an accumulating memory leak in JSON parsing large (outside of the range [-2^63, 2^64 - 1]) integers. The leaked memory is a copy of the string form of the integer plus an additional NULL byte. The leak occurs irrespective of whether the integer parses successfully or is rejected due to having more than sys.get_int_max_str_digits() digits, meaning that any sized leak per malicious JSON can be achieved provided that there is no limit on the overall size of the payload. Any service that calls ujson.load()/ujson.loads()/ujson.decode() on untrusted inputs is affected and vulnerable to denial of service attacks. This issue has been fixed in version 5.12.0.

CVSS Base Scores

version 3.1