# CVE-2017-18258: libxml2: The xz_head function in xzlib.c in libxml2 before 2.9.6 allows remote attackers to cause a denial of service (memory...

CVE-2017-18258 is fixed in 4 products on 1 platform, first by libxml2 2.9.4+dfsg1-6.1ubuntu1.2, released July 30, 2018. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2017-18258
- Priority: Routine
- CVSS: n/a (Low)
- EPSS: 0.0273
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 7, 2018

## Description

The xz_head function in xzlib.c in libxml2 before 2.9.6 allows remote attackers to cause a denial of service (memory consumption) via a crafted LZMA file, because the decoder functionality does not restrict memory usage to what is required for a legitimate file.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libxml2 Ubuntu 18.04.6 LTS (bionic) | 2.9.4+dfsg1-6.1ubuntu1.2 | [libxml2 2.9.4+dfsg1-6.1ubuntu1.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libxml2-2.9.4-dfsg1-6.1ubuntu1.2.md) | Jul 30, 2018 |
| Linux | libxml2-utils Ubuntu 18.04.6 LTS (bionic) | 2.9.4+dfsg1-6.1ubuntu1.2 | [libxml2-utils 2.9.4+dfsg1-6.1ubuntu1.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libxml2-utils-2.9.4-dfsg1-6.1ubuntu1.2.md) | Jul 30, 2018 |
| Linux | python-libxml2 Ubuntu 18.04.6 LTS (bionic) | 2.9.4+dfsg1-6.1ubuntu1.2 | [python-libxml2 2.9.4+dfsg1-6.1ubuntu1.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python-libxml2-2.9.4-dfsg1-6.1ubuntu1.2.md) | Jul 30, 2018 |
| Linux | python3-libxml2 Ubuntu 18.04.6 LTS (bionic) | 2.9.4+dfsg1-6.1ubuntu1.2 | [python3-libxml2 2.9.4+dfsg1-6.1ubuntu1.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python3-libxml2-2.9.4-dfsg1-6.1ubuntu1.2.md) | Jul 30, 2018 |

---

Data as of 2026-11-07T06:34:28Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo