This libpng update fixes the following two overflow security issues.
* bnc#873123: Fixed integer overflow that could have lead to a heap-based buffer overflow in png_set_sPLT() and png_set_text_2() (CVE-2013-7354). * bnc#873124: Fixed integer overflow that could have lead to a heap-based buffer overflow in png_set_unknown_chunks() (CVE-2013-7353).