=========================================================================Ubuntu Security Notice USN-2861-1
January 06, 2016

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

- Ubuntu 15.10
- Ubuntu 15.04
- Ubuntu 14.04 LTS
- Ubuntu 12.04 LTS

Summary:

libpng could be made to crash or run programs as your login if it opened a
specially crafted file.

Software Description:
- libpng: PNG (Portable Network Graphics) file library

Details:

It was discovered that libpng incorrectly handled certain small bit-depth
values. If a user or automated system using libpng were tricked into
opening a specially crafted image, an attacker could exploit this to cause
a denial of service or execute code with the privileges of the user
invoking the program. (CVE-2015-8472)

Qixue Xiao and Chen Yu discovered that libpng incorrectly handled certain
malformed images. If a user or automated system using libpng were tricked
into opening a specially crafted image, an attacker could exploit this to
cause a denial of service. (CVE-2015-8540)

Update instructions:

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

Ubuntu 15.10:
  libpng12-0                      1.2.51-0ubuntu3.15.10.2

Ubuntu 15.04:
  libpng12-0                      1.2.51-0ubuntu3.15.04.2

Ubuntu 14.04 LTS:
  libpng12-0                      1.2.50-1ubuntu2.14.04.2

Ubuntu 12.04 LTS:
  libpng12-0                      1.2.46-3ubuntu4.2

After a standard system update you need to restart your session to make
all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-2861-1
  CVE-2015-8472, CVE-2015-8540

Package Information:
  https://launchpad.net/ubuntu/+source/libpng/1.2.51-0ubuntu3.15.10.2
  https://launchpad.net/ubuntu/+source/libpng/1.2.51-0ubuntu3.15.04.2
  https://launchpad.net/ubuntu/+source/libpng/1.2.50-1ubuntu2.14.04.2
  https://launchpad.net/ubuntu/+source/libpng/1.2.46-3ubuntu4.2