Bug 1895295 (CVE-2020-25697)

Summary:	CVE-2020-25697 xorg-x11-server: local privilege escalation
Product:	[Other] Security Response	Reporter:	msiddiqu
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	ajax, bskeggs, caillon+fedoraproject, carnil, jglisse, ofourdan, peter.hutterer, rhughes, rstrode, sandmann, security-response-team, xgl-maint
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:	A privilege escalation flaw was found in the Xorg-x11-server due to a lack of authentication for X11 clients. This flaw allows an attacker to take control of an X application by impersonating the server it is expecting to connect to.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-11-24 17:34:02 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:	1896017, 1896018, 1910619
Bug Blocks:	1895294, 1939827

Description msiddiqu 2020-11-06 09:13:26 UTC

While X11 servers authenticate their clients, X11 clients *do not* authenticate the server.  This can be exploited to take control of an X application by impersonating the server it is expecting to connect to.

Comment 1 msiddiqu 2020-11-09 16:11:33 UTC

Public via:

https://www.openwall.com/lists/oss-security/2020/11/09/3

Comment 2 msiddiqu 2020-11-09 16:13:59 UTC

Created libX11 tracking bugs for this issue:

Affects: fedora-all [bug 1896017]


Created xorg-x11-server tracking bugs for this issue:

Affects: fedora-all [bug 1896018]

Comment 4 Huzaifa S. Sidhpurwala 2020-11-11 05:06:43 UTC

External References:

https://www.openwall.com/lists/oss-security/2020/11/09/3

Comment 5 Product Security DevOps Team 2020-11-24 17:34:02 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2020-25697

Comment 6 Huzaifa S. Sidhpurwala 2020-12-08 05:57:29 UTC

Statement:

As per upstream, exploiting this flaw is non-trivial and it requires exact timing on the behalf of the attacker. Many graphical applications exit if their connection to the X server is lost, so a typical desktop session is either impossible or difficult to exploit. There is currently no upstream patch available for this flaw.