# CVE-2018-18020: libqpdf21: In QPDF 8.2.1, in libqpdf/QPDFWriter.cc, QPDFWriter::unparseObject and QPDFWriter::unparseChild have recursive calls...

CVE-2018-18020 is fixed in 2 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-2018-18020
- Priority: Routine
- CVSS: n/a (Low)
- EPSS: 0.0121
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 6, 2018

## Description

In QPDF 8.2.1, in libqpdf/QPDFWriter.cc, QPDFWriter::unparseObject and QPDFWriter::unparseChild have recursive calls for a long time, which allows remote attackers to cause a denial of service via a crafted PDF file.

## 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 | 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 |

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Data as of 2026-11-07T18:46:35Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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