Integer overflow in ultrajson - CVE-2026-32875
Published: April 27, 2026
Vulnerability identifier: #VU128153
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-32875
CWE-ID: CWE-190
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to integer overflow or underflow in ujson.dumps() indentation handling when processing user-controlled indent values during JSON serialization of nested input. A remote attacker can supply a specially crafted indent value to cause a denial of service.
The issue can result in a segmentation fault when the indent value and nesting depth exceed INT32_MAX, or an infinite loop when a large negative indent is used.
Affected software
ultrajson
IBM Watson Speech Services Cartridge for IBM Cloud Pak for Data
Fedora
Ubuntu
ujson (Ubuntu package)
python-ujson
IBM Watson Speech Services Cartridge for IBM Cloud Pak for Data
Fedora
Ubuntu
ujson (Ubuntu package)
python-ujson
How to mitigate CVE-2026-32875
Install security update from vendor's website.
ultrajson - update to 5.12.0
IBM Watson Speech Services Cartridge for IBM Cloud Pak for Data - update to 5.3.1 Patch 5
ujson (Ubuntu package) - addressed in versions 5.1.0-1ubuntu0.1~esm2, 5.9.0-1ubuntu0.1~esm1, 5.10.0-1ubuntu0.1, 5.11.0-3ubuntu0.1
python-ujson - update to 5.8.0-2.el9
IBM Watson Speech Services Cartridge for IBM Cloud Pak for Data - update to 5.3.1 Patch 5
ujson (Ubuntu package) - addressed in versions 5.1.0-1ubuntu0.1~esm2, 5.9.0-1ubuntu0.1~esm1, 5.10.0-1ubuntu0.1, 5.11.0-3ubuntu0.1
python-ujson - update to 5.8.0-2.el9