Bug 1661120 (CVE-2018-20021)

Summary:	CVE-2018-20021 libvncserver: Infinite loop in VNC client code allows for denial of service
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:	negativo17, ppisar, rdieter
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-06-10 10:44:24 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:	1661121, 1661122, 1663001
Bug Blocks:	1661105

Description Sam Fowler 2018-12-20 07:09:10 UTC

LibVNC before commit c3115350eb8bb635d0fdb4dbbb0d0541f38ed19c contains a CWE-835: Infinite loop vulnerability in VNC client code. Vulnerability allows attacker to consume excessive amount of resources like CPU and RAM


External Reference:

https://ics-cert.kaspersky.com/advisories/klcert-advisories/2018/12/19/klcert-18-031-libvnc-infinite-loop/


Upstream Patch:

https://github.com/LibVNC/libvncserver/commit/c3115350eb8bb635d0fdb4dbbb0d0541f38ed19c

Comment 1 Sam Fowler 2018-12-20 07:09:24 UTC

Created libvncserver tracking bugs for this issue:

Affects: epel-7 [bug 1661122]
Affects: fedora-all [bug 1661121]

Comment 2 Sam Fowler 2018-12-20 07:40:16 UTC

Upstream Issue:

https://github.com/LibVNC/libvncserver/issues/251

Comment 3 Stefan Cornelius 2018-12-21 11:05:54 UTC

I suspect that this was introduced by https://github.com/LibVNC/libvncserver/commit/79d938c16bf7a14b6d6ee290bcfef3c01f9c4f02 - which fixed a divbyzero.