Bug 1860334 (CVE-2020-14403)

Summary:	CVE-2020-14403 libvncserver: libvncserver/hextile.c allows out-of-bounds access via encodings
Product:	[Other] Security Response	Reporter:	Marian Rehak <mrehak>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	jadahl, negativo17, oholy, rdieter
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	libvncserver 0.9.13	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-11-02 17:18:31 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:	1860335, 1860336, 1862183, 1862184, 1862185, 1862186
Bug Blocks:	1860332

Description Marian Rehak 2020-07-24 10:24:43 UTC

An issue was discovered in LibVNCServer before 0.9.13. libvncserver/hextile.c allows out-of-bounds access via encodings.

Upstream commit:

https://github.com/LibVNC/libvncserver/commit/74e8a70f2c9a5248d6718ce443e07c7ed314dfff

Comment 1 Marian Rehak 2020-07-24 10:25:31 UTC

Created libvncserver tracking bugs for this issue:

Affects: epel-7 [bug 1860335]
Affects: fedora-all [bug 1860336]

Comment 2 Todd Cullum 2020-07-30 16:47:31 UTC

in libvncserver/hextile.c's subrectEncode##bpp() rectangle encoder, there's a potential out-of-bounds read due to && operator order. The patch reverses the order. This flaw could potentially cause undefined behavior or a crash if the width (w) is incorrect.