RHSA-2015:2594: Moderate: libpng security update

The libpng packages contain a library of functions for creating andmanipulating PNG (Portable Network Graphics) image format files.It was discovered that the pnggetPLTE() and pngsetPLTE() functions oflibpng did not correctly calculate the maximum palette sizes for bit depthsof less than 8. In case an application tried to use these functions incombination with properly calculated palette sizes, this could lead to abuffer overflow or out-of-bounds reads. An attacker could exploit this tocause a crash or potentially execute arbitrary code by tricking anunsuspecting user into processing a specially crafted PNG image. However,the exact impact is dependent on the application using the library.(CVE-2015-8126, CVE-2015-8472)An array-indexing error was discovered in the pngconverttorfc1123()function of libpng. An attacker could possibly use this flaw to cause anout-of-bounds read by tricking an unsuspecting user into processing aspecially crafted PNG image. (CVE-2015-7981)All libpng users are advised to upgrade to these updated packages, whichcontain backported patches to correct these issues.