Bug 1519082 (CVE-2017-16611)

Summary:	CVE-2017-16611 libXfont: User can trigger arbitrary file read by X server causing a DoS
Product:	[Other] Security Response	Reporter:	Sam Fowler <sfowler>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	ajax, alexl, btissoir, caillon+fedoraproject, fonts-bugs, jglisse, john.j5live, rhughes, rstrode, sandmann
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	libXfont 1.5.4, libXfont2 2.0.3	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2017-12-01 04:30:53 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1519083, 1519084
Bug Blocks:	1519085

Description Sam Fowler 2017-11-30 05:42:54 UTC

A low privileged user can create symlinks to trigger arbitrary file reads by X server. Under certain configurations, a user can create a symlink to special files (e.g. /dev/watchdog) to cause a denial of service.

A non-privileged X client can instruct X server running under root to open any file by creating a directory with symlinks(s) named "fonts.dir", "fonts.alias" or any font file to link to any other file in the system. X server will follow the symlink and open and read the file. When opened and under certain configurations, special files like /dev/watchdog can trigger system operations (e.g. reboot).

References:
http://openwall.com/lists/oss-security/2017/11/28/7
https://cgit.freedesktop.org/xorg/lib/libXfont/commit/?h=libXfont-1.5-branch&id=5ed8ac0e4f063825b8ecda48e9a111d3ce92e825
https://cgit.freedesktop.org/xorg/lib/libXfont/commit/?id=7b377456f95d2ec3ead40f4fb74ea620191f88c8

Comment 1 Sam Fowler 2017-11-30 05:43:16 UTC

Created libXfont tracking bugs for this issue:

Affects: fedora-all [bug 1519084]


Created libXfont2 tracking bugs for this issue:

Affects: fedora-all [bug 1519083]