Ubuntu USN · USN-8219-1

UltraJSON vulnerabilities

Published: Tue, 28 Apr 2026 17:32

CVE-2026-32875CVE-2026-32874

Summary

Several security issues were fixed in UltraJSON.

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)

Recommended actions per Ubuntu release

StackPatch playbook auto-generated per release codename and per affected package.

Ubuntu jammy

ujson→5.1.0-1ubuntu0.1~esm2apt_upgrade_esm
Fixed at 5.1.0-1ubuntu0.1~esm2 — ESM-only. Enable Ubuntu Pro (free for 5 personal machines) or treat as watch item.
```
sudo pro attach <token>
sudo apt-get update
sudo apt-get install --only-upgrade -y ujson=5.1.0-1ubuntu0.1~esm2
```
Sign up at https://ubuntu.com/pro. Free for personal + small-team use.
python3-ujson→5.1.0-1ubuntu0.1~esm2apt_upgrade_esm
Fixed at 5.1.0-1ubuntu0.1~esm2 — ESM-only. Enable Ubuntu Pro (free for 5 personal machines) or treat as watch item.
```
sudo pro attach <token>
sudo apt-get update
sudo apt-get install --only-upgrade -y python3-ujson=5.1.0-1ubuntu0.1~esm2
```
Sign up at https://ubuntu.com/pro. Free for personal + small-team use.

Ubuntu noble

ujson→5.9.0-1ubuntu0.1~esm1apt_upgrade_esm
Fixed at 5.9.0-1ubuntu0.1~esm1 — ESM-only. Enable Ubuntu Pro (free for 5 personal machines) or treat as watch item.
```
sudo pro attach <token>
sudo apt-get update
sudo apt-get install --only-upgrade -y ujson=5.9.0-1ubuntu0.1~esm1
```
Sign up at https://ubuntu.com/pro. Free for personal + small-team use.
python3-ujson→5.9.0-1ubuntu0.1~esm1apt_upgrade_esm
Fixed at 5.9.0-1ubuntu0.1~esm1 — ESM-only. Enable Ubuntu Pro (free for 5 personal machines) or treat as watch item.
```
sudo pro attach <token>
sudo apt-get update
sudo apt-get install --only-upgrade -y python3-ujson=5.9.0-1ubuntu0.1~esm1
```
Sign up at https://ubuntu.com/pro. Free for personal + small-team use.

Ubuntu questing

ujson→5.10.0-1ubuntu0.1apt_upgrade
Standard apt upgrade. Install 5.10.0-1ubuntu0.1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y ujson
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
python3-ujson→5.10.0-1ubuntu0.1apt_upgrade
Standard apt upgrade. Install 5.10.0-1ubuntu0.1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y python3-ujson
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

Ubuntu resolute

ujson→5.11.0-3ubuntu0.1apt_upgrade
Standard apt upgrade. Install 5.11.0-3ubuntu0.1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y ujson
```
Most apt upgrades restart their service automatically. needrestart lists anything else.
python3-ujson→5.11.0-3ubuntu0.1apt_upgrade
Standard apt upgrade. Install 5.11.0-3ubuntu0.1 from the apt repo.
```
sudo apt-get update
sudo apt-get install --only-upgrade -y python3-ujson
```
Most apt upgrades restart their service automatically. needrestart lists anything else.

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