Off-by-one error in the bmp_rle4_fread function in pngxrbmp.c in OptiPNG before 0.7.6 allows remote attackers to cause a denial of service (out-of-bounds read or write access and crash) or possibly execute arbitrary code via a crafted image file, which triggers a heap-based buffer overflow.
https://sourceforge.net/p/optipng/bugs/57/
https://security.gentoo.org/glsa/201608-01
http://www.ubuntu.com/usn/USN-2951-1
http://www.debian.org/security/2016/dsa-3546
http://lists.opensuse.org/opensuse-updates/2016-04/msg00065.html
http://lists.opensuse.org/opensuse-updates/2016-04/msg00061.html