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Ubuntu Security Notice USN-2365-1
September 29, 2014

libvncserver vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 14.04 LTS
- Ubuntu 12.04 LTS

Summary:

Several security issues were fixed in LibVNCServer.

Software Description:
- libvncserver: vnc server library

Details:

Nicolas Ruff discovered that LibVNCServer incorrectly handled memory when
being advertised large screen sizes by the server. If a user were tricked
into connecting to a malicious server, an attacker could use this issue to
cause a denial of service, or possibly execute arbitrary code.
(CVE-2014-6051, CVE-2014-6052)

Nicolas Ruff discovered that LibVNCServer incorrectly handled large
ClientCutText messages. A remote attacker could use this issue to cause a
server to crash, resulting in a denial of service. (CVE-2014-6053)

Nicolas Ruff discovered that LibVNCServer incorrectly handled zero scaling
factor values. A remote attacker could use this issue to cause a server to
crash, resulting in a denial of service. (CVE-2014-6054)

Nicolas Ruff discovered that LibVNCServer incorrectly handled memory in the
file transfer feature. A remote attacker could use this issue to cause a
server to crash, resulting in a denial of service, or possibly execute
arbitrary code. (CVE-2014-6055)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 14.04 LTS:
  libvncserver0                   0.9.9+dfsg-1ubuntu1.1

Ubuntu 12.04 LTS:
  libvncserver0                   0.9.8.2-2ubuntu1.1

In general, a standard system update will make all the necessary changes.

References:
  http://www.ubuntu.com/usn/usn-2365-1
  CVE-2014-6051, CVE-2014-6052, CVE-2014-6053, CVE-2014-6054,
  CVE-2014-6055

Package Information:
  https://launchpad.net/ubuntu/+source/libvncserver/0.9.9+dfsg-1ubuntu1.1
  https://launchpad.net/ubuntu/+source/libvncserver/0.9.8.2-2ubuntu1.1