CVE-2017-18258

Publication date 8 April 2018

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

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.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
libxml2	18.04 LTS bionic	Fixed 2.9.4+dfsg1-6.1ubuntu1.2
	17.10 artful	Ignored end of life
	16.04 LTS xenial	Fixed 2.9.3+dfsg1-1ubuntu0.6
	14.04 LTS trusty	Fixed 2.9.1+dfsg1-3ubuntu4.13

Notes

leosilva

precise/esm hasn't support for LZMA

ccdm94

the fix for this issue seems to introduce the vulnerability related to CVE-2018-9251.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
libxml2	Upstream: ?id=e2a

Severity score breakdown

Parameter	Value
Base score	6.5 · Medium
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	Required
Scope	Unchanged
Confidentiality	None
Integrity impact	None
Availability impact	High
Vector	CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H