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[USN-8219-1] UltraJSON vulnerabilities

Posted on 28 April 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8219-1
April 28, 2026

ujson vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 26.04 LTS
- Ubuntu 25.10
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS

Summary:

Several security issues were fixed in UltraJSON.

Software Description:
- ujson: Ultra fast JSON encoder and decoder

Details:

Cameron Criswell discovered that UltraJSON contained a memory leak
that would occur when parsing large integers. An attacker could
possibly use this issue to cause UltraJSON to crash, resulting in a
denial of service. This issue only affected Ubuntu 24.04 LTS,
Ubuntu 25.10, and Ubuntu 26.04 LTS. (CVE-2026-32874)

It was discovered that UltraJSON contained integer overflow/underflow
issues when calculating how much memory to reserve for indentation in
certain instances. An attacker could possibly use this issue to cause
UltraJSON to crash, resulting in a denial of service. (CVE-2026-32875)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 26.04 LTS
python3-ujson 5.11.0-3ubuntu0.1

Ubuntu 25.10
python3-ujson 5.10.0-1ubuntu0.1

Ubuntu 24.04 LTS
python3-ujson 5.9.0-1ubuntu0.1~esm1
Available with Ubuntu Pro

Ubuntu 22.04 LTS
python3-ujson 5.1.0-1ubuntu0.1~esm2
Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-8219-1
CVE-2026-32874, CVE-2026-32875

Package Information:
https://launchpad.net/ubuntu/+source/ujson/5.11.0-3ubuntu0.1
https://launchpad.net/ubuntu/+source/ujson/5.10.0-1ubuntu0.1

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