Arch Linux: 201701-20 Critical: libvncserver Arbitrary Code Execution

Arch Linux Security Advisory ASA-201701-20
=========================================
Severity: Critical
Date    : 2017-01-13
CVE-ID  : CVE-2016-9941 CVE-2016-9942
Package : libvncserver
Type    : arbitrary code execution
Remote  : Yes
Link    : https://security.archlinux.org/AVG-124

Summary
======
The package libvncserver before version 0.9.11-1 is vulnerable to
arbitrary code execution.

Resolution
=========
Upgrade to 0.9.11-1.

# pacman -Syu "libvncserver>=0.9.11-1"

The problems have been fixed upstream in version 0.9.11.

Workaround
=========
None.

Description
==========
- CVE-2016-9941 (arbitrary code execution)

A heap-based buffer overflow has been discovered in rfbproto.c in the
LibVNCClient part of LibVNCServer before 0.9.11 allows remote servers
to cause a denial of service (application crash) or possibly execute
arbitrary code via a crafted FramebufferUpdate message containing a
subrectangle outside of the client drawing area.

- CVE-2016-9942 (arbitrary code execution)

A heap-based buffer overflow has been discovered in ultra.c in
LibVNCClient in LibVNCServer before 0.9.11 allows remote servers to
cause a denial of service (application crash) or possibly execute
arbitrary code via a crafted FramebufferUpdate message with the Ultra
type tile, such that the LZO payload decompressed length exceeds what
is specified by the tile dimensions.

Impact
=====
A remote attacker is able to use specially crafted messages to execute
arbitrary code on the affected host.

References
=========
https://bugs.archlinux.org/task/52481
https://github.com/LibVNC/libvncserver/pull/137
https://security.archlinux.org/CVE-2016-9941
https://security.archlinux.org/CVE-2016-9942