(RHSA-2011:1104) Moderate: libpng security update

The libpng packages contain a library of functions for creating and
manipulating PNG (Portable Network Graphics) image format files.

A buffer overflow flaw was found in the way libpng processed certain PNG
image files. An attacker could create a specially-crafted PNG image that,
when opened, could cause an application using libpng to crash or,
potentially, execute arbitrary code with the privileges of the user running
the application. (CVE-2011-2690)

Note: The application behavior required to exploit CVE-2011-2690 is rarely
used. No application shipped with Red Hat Enterprise Linux behaves this
way, for example.

An uninitialized memory read issue was found in the way libpng processed
certain PNG images that use the Physical Scale (sCAL) extension. An
attacker could create a specially-crafted PNG image that, when opened,
could cause an application using libpng to crash. (CVE-2011-2692)

Users of libpng should upgrade to these updated packages, which contain
backported patches to correct these issues. All running applications using
libpng must be restarted for the update to take effect.