# CVE-2021-45958: ujson: UltraJSON (aka ujson) through 5.1.0 has a stack-based buffer overflow in Buffer_AppendIndentUnchecked (called from en...

CVE-2021-45958 is fixed in 3 products on 1 platform, first by python3-ujson 1.35-4ubuntu0.1, released December 31, 2021. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-45958
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0167
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Dec 31, 2021

## Description

UltraJSON (aka ujson) through 5.1.0 has a stack-based buffer overflow in Buffer_AppendIndentUnchecked (called from encode). Exploitation can, for example, use a large amount of indentation.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | python-ujson Ubuntu 18.04.6 LTS (bionic) | 1.35-2ubuntu0.1~esm1 | [python-ujson 1.35-2ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python-ujson-1.35-2ubuntu0.1-esm1.md) | Jul 5, 2022 |
| Linux | python3-ujson Ubuntu 18.04.6 LTS (bionic) | 1.35-2ubuntu0.1~esm1 | [python3-ujson 1.35-2ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python3-ujson-1.35-2ubuntu0.1-esm1.md) | Jul 5, 2022 |
| Linux | python3-ujson Ubuntu 20.04 LTS (focal) | 1.35-4ubuntu0.1 | [python3-ujson 1.35-4ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-python3-ujson-1.35-4ubuntu0.1.md) | Dec 31, 2021 |
| Linux | python3-ujson Ubuntu 22.04.1 LTS (jammy) | 5.1.0-1ubuntu0.1~esm1 | [python3-ujson 5.1.0-1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-python3-ujson-5.1.0-1ubuntu0.1-esm1.md) | Jul 5, 2022 |
| Linux | ujson Debian 12.15 (bookworm) | 5.2.0-1 | [DEBIAN-CVE-2021-45958](https://patchblox.com/security/data/fix/linux/debian-cve-2021-45958.md) | Jan 1, 2022 |
| Linux | ujson Debian 13.5 (trixie) | 5.2.0-1 | [DEBIAN-CVE-2021-45958](https://patchblox.com/security/data/fix/linux/debian-cve-2021-45958.md) | Jan 1, 2022 |
| Linux | ujson Debian 14 | 5.2.0-1 | [DEBIAN-CVE-2021-45958](https://patchblox.com/security/data/fix/linux/debian-cve-2021-45958.md) | Jan 1, 2022 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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