The png_do_expand_palette function in libpng before 1.6.8 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via (1) a PLTE chunk of zero bytes or (2) a NULL palette, related to pngrtran.c and pngset.c.Per: http://cwe.mitre.org/data/definitions/476.html CWE-476: NULL Pointer Dereference http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2013-6954
