(RHSA-2011:0871) Moderate: tigervnc 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. TigerVNC is a suite of VNC servers and clients.

It was discovered that vncviewer could prompt for and send authentication
credentials to a remote server without first properly validating the
server’s X.509 certificate. As vncviewer did not indicate that the
certificate was bad or missing, a man-in-the-middle attacker could use this
flaw to trick a vncviewer client into connecting to a spoofed VNC server,
allowing the attacker to obtain the client’s credentials. (CVE-2011-1775)

All tigervnc users should upgrade to these updated packages, which contain
a backported patch to correct this issue.