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Ubuntu Security Notice USN-1175-1
July 26, 2011

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

- Ubuntu 11.04
- Ubuntu 10.10
- Ubuntu 10.04 LTS
- Ubuntu 8.04 LTS

Summary:

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

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

Details:

Frank Busse discovered that libpng did not properly handle certain
malformed PNG images. If a user or automated system were tricked into
opening a crafted PNG file, an attacker could cause libpng to crash,
resulting in a denial of service. This issue only affected Ubuntu
10.04 LTS, 10.10, and 11.04. (CVE-2011-2501)

It was discovered that libpng did not properly handle certain malformed PNG
images. If a user or automated system were tricked into opening a crafted
PNG file, an attacker could cause a denial of service or possibly execute
arbitrary code with the privileges of the user invoking the program.
(CVE-2011-2690)

Frank Busse discovered that libpng did not properly handle certain PNG
images with invalid sCAL chunks. If a user or automated system were tricked
into opening a crafted PNG file, an attacker could cause a denial of
service or possibly execute arbitrary code with the privileges of the user
invoking the program. (CVE-2011-2692)

Update instructions:

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

Ubuntu 11.04:
  libpng12-0                      1.2.44-1ubuntu3.1

Ubuntu 10.10:
  libpng12-0                      1.2.44-1ubuntu0.1

Ubuntu 10.04 LTS:
  libpng12-0                      1.2.42-1ubuntu2.2

Ubuntu 8.04 LTS:
  libpng12-0                      1.2.15~beta5-3ubuntu0.4

After a standard system update you need to reboot your computer to make
all the necessary changes.

References:
  http://www.ubuntu.com/usn/usn-1175-1
  CVE-2011-2501, CVE-2011-2690, CVE-2011-2692

Package Information:
  https://launchpad.net/ubuntu/+source/libpng/1.2.44-1ubuntu3.1
  https://launchpad.net/ubuntu/+source/libpng/1.2.44-1ubuntu0.1
  https://launchpad.net/ubuntu/+source/libpng/1.2.42-1ubuntu2.2
  https://launchpad.net/ubuntu/+source/libpng/1.2.15~beta5-3ubuntu0.4