RHSA-2011:0871 - Security Advisory

Topic

Updated tigervnc packages that fix one security issue are now available for
Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having moderate
security impact. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available from the CVE link in
the References section.

Description

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.

Solution

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

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

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.1 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.1 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.1 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.1 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.1 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.1 i386
• Red Hat Virtual Storage Appliance (from RHUI) 6.1 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 702470 - CVE-2011-1775 tigervnc: vncviewer can send password to server without proper validation of the X.509 certificate

CVEs

• CVE-2011-1775

References

• https://access.redhat.com/security/updates/classification/#moderate