Buffer overflow in the png_read_IDAT_data function in pngrutil.c in libpng before 1.5.21 and 1.6.x before 1.6.16 allows context-dependent attackers to execute arbitrary code via IDAT data with a large width, a different vulnerability than CVE-2014-9495. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-0973