(RHSA-2009:0261) Moderate: vnc security update

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.