Moderate: vnc security update

Updated vnc packages to correct a security issue are now available for Red
Hat Enterprise Linux 3, 4, and 5.

This update has been rated as having moderate security impact by the Red
Hat Security Response Team.

Virtual Network Computing (VNC) is a remote display system which allows you
to view a computer's "desktop" environment not only on the machine where it
is running, but from anywhere on the Internet and from a wide variety of
machine architectures.

An insufficient input validation flaw was discovered in the VNC client
application, vncviewer. If an attacker could convince a victim to connect
to a malicious VNC server, or when an attacker was able to connect to
vncviewer running in the "listen" mode, the attacker could cause the
victim's vncviewer to crash or, possibly, execute arbitrary code.
(CVE-2008-4770)

Users of vncviewer should upgrade to these updated packages, which contain
a backported patch to resolve this issue. For the update to take effect,
all running instances of vncviewer must be restarted after the update is
installed.

Before applying this update, make sure that all previously-released
errata relevant to your system have been applied.

This update is available via Red Hat Network. Details on how to use
the Red Hat Network to apply this update are available at
http://kbase.redhat.com/faq/docs/DOC-11259

471777 - VNC Free Edition 4.1.3 fixes a possible security vulnerability only present in the listening viewer. VNC Server is not compromised.
480590 - CVE-2008-4770 vnc: vncviewer insufficient encoding value validation in CMsgReader::readRect

https://www.redhat.com/security/data/cve/CVE-2008-4770.html
http://www.redhat.com/security/updates/classification/#moderate