Emacs 21 allows user-assisted attackers to cause a denial of service (crash) via certain crafted images, as demonstrated via a GIF image in vm mode, related to image size calculation.
https://issues.rpath.com/browse/RPL-1490
http://www.ubuntu.com/usn/usn-504-1
http://www.securitytracker.com/id?1018277
http://www.securityfocus.com/bid/24570
http://www.novell.com/linux/security/advisories/2007_19_sr.html
http://www.mandriva.com/security/advisories?name=MDKSA-2007:133
http://www.debian.org/security/2007/dsa-1316