# CVE-2021-36978: qpdf: QPDF 9.x through 9.1.1 and 10.x through 10.0.4 has a heap-based buffer overflow in Pl_ASCII85Decoder::write (called f...

CVE-2021-36978 is fixed in 3 products on 1 platform, first by libqpdf21 8.0.2-3ubuntu0.1, released August 11, 2023. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-36978
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.0127
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 20, 2021

## Description

QPDF 9.x through 9.1.1 and 10.x through 10.0.4 has a heap-based buffer overflow in Pl_ASCII85Decoder::write (called from Pl_AES_PDF::flush and Pl_AES_PDF::finish) when a certain downstream write fails.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libqpdf21 Ubuntu 18.04.6 LTS (bionic) | 8.0.2-3ubuntu0.1 | [libqpdf21 8.0.2-3ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libqpdf21-8.0.2-3ubuntu0.1.md) | Aug 11, 2023 |
| Linux | libqpdf26 Ubuntu 20.04 LTS (focal) | 9.1.1-1ubuntu0.1 | [libqpdf26 9.1.1-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libqpdf26-9.1.1-1ubuntu0.1.md) | Aug 11, 2023 |
| Linux | qpdf Ubuntu 18.04.6 LTS (bionic) | 8.0.2-3ubuntu0.1 | [qpdf 8.0.2-3ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-qpdf-8.0.2-3ubuntu0.1.md) | Aug 11, 2023 |
| Linux | qpdf Ubuntu 20.04 LTS (focal) | 9.1.1-1ubuntu0.1 | [qpdf 9.1.1-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-qpdf-9.1.1-1ubuntu0.1.md) | Aug 11, 2023 |

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Data as of 2026-11-09T07:25:28Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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