The bmp_read_rows function in pngxtern/pngxrbmp.c in OptiPNG before 0.7.6 allows remote attackers to cause a denial of service (invalid memory write and crash) via a series of delta escapes in a crafted BMP image.
https://sourceforge.net/p/optipng/bugs/59/
https://security.gentoo.org/glsa/201608-01
http://www.ubuntu.com/usn/USN-2951-1
http://www.securityfocus.com/archive/1/537972/100/0/threaded
http://www.openwall.com/lists/oss-security/2016/04/04/2
http://www.debian.org/security/2016/dsa-3546
http://seclists.org/fulldisclosure/2016/Apr/15
http://lists.opensuse.org/opensuse-updates/2016-04/msg00065.html
http://lists.opensuse.org/opensuse-updates/2016-04/msg00061.html