---
id: CVE-2017-18258
title: >-
  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 requir…
summary: >-
  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 requir…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'
cwe:
  - CWE-770
vendor: xmlsoft
product: libxml2
affected:
  - libxml2 < 2.9.6
patched:
  - libxml2 2.9.6
published: '2018-04-08'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T07:16:40.117'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2017-18258'
references:
  - url: >-
      https://git.gnome.org/browse/libxml2/commit/?id=e2a9122b8dde53d320750451e9907a7dcb2ca8bb
    label: cve@mitre.org
  - url: 'https://kc.mcafee.com/corporate/index?page=content&id=SB10284'
    label: cve@mitre.org
  - url: 'https://lists.debian.org/debian-lts-announce/2018/09/msg00035.html'
    label: cve@mitre.org
  - url: 'https://lists.debian.org/debian-lts-announce/2020/09/msg00009.html'
    label: cve@mitre.org
  - url: 'https://security.netapp.com/advisory/ntap-20190719-0001/'
    label: cve@mitre.org
  - url: 'https://usn.ubuntu.com/3739-1/'
    label: cve@mitre.org
  - url: >-
      https://git.gnome.org/browse/libxml2/commit/?id=e2a9122b8dde53d320750451e9907a7dcb2ca8bb
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://kc.mcafee.com/corporate/index?page=content&id=SB10284'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2018/09/msg00035.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2020/09/msg00009.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.netapp.com/advisory/ntap-20190719-0001/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://usn.ubuntu.com/3739-1/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
epss: 0.02655
epssPercentile: 0.85297
ingestedAt: '2026-10-14T07:21:04.799Z'
---

## Overview

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.

## Affected

- `libxml2 < 2.9.6`

## Remediation

Upgrade past the affected range:

- `libxml2 2.9.6`