Bug 1661136 (CVE-2018-6307)

Summary:	CVE-2018-6307 libvncserver: Use-after-free in file transfer extension server code allows for potential code execution
Product:	[Other] Security Response	Reporter:	Sam Fowler <sfowler>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
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:	2018-12-21 10:42:31 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:	1661137, 1661138
Bug Blocks:	1661105

Description Sam Fowler 2018-12-20 07:23:13 UTC

LibVNC before commit ca2a5ac02fbbadd0a21fabba779c1ea69173d10b contains heap use-after-free vulnerability in server code of file transfer extension that can result remote code execution.


External Reference:

https://ics-cert.kaspersky.com/advisories/klcert-advisories/2018/12/19/klcert-18-026-libvnc-heap-use-after-free/


Upstream Patch:

https://github.com/LibVNC/libvncserver/commit/ca2a5ac02fbbadd0a21fabba779c1ea69173d10b

Comment 1 Sam Fowler 2018-12-20 07:23:26 UTC

Created libvncserver tracking bugs for this issue:

Affects: epel-7 [bug 1661138]
Affects: fedora-all [bug 1661137]

Comment 2 Sam Fowler 2018-12-20 07:33:50 UTC

Upstream Issue:

https://github.com/LibVNC/libvncserver/issues/241

Comment 3 Sam Fowler 2018-12-20 08:02:04 UTC

Reference:

https://seclists.org/oss-sec/2018/q4/212

Comment 4 Stefan Cornelius 2018-12-21 10:42:33 UTC

Statement:

This issue did not affect the versions of libvncserver as shipped with Red Hat Enterprise Linux 6 and 7, as they did not include support for tightvnc file transfer.