The png_err function in pngerror.c in libpng 1.0.x before 1.0.55, 1.2.x before 1.2.45, 1.4.x before 1.4.8, and 1.5.x before 1.5.4 makes a function call using a NULL pointer argument instead of an empty-string argument, which allows remote attackers to cause a denial of service (application crash) via a crafted PNG image.
https://exchange.xforce.ibmcloud.com/vulnerabilities/68537
http://www.securityfocus.com/bid/48660
http://www.openwall.com/lists/oss-security/2011/07/13/2
http://www.libpng.org/pub/png/libpng.html
http://www.debian.org/security/2011/dsa-2287
http://support.apple.com/kb/HT5002
http://security.gentoo.org/glsa/glsa-201206-15.xml
http://marc.info/?l=bugtraq&m=133951357207000&w=2
http://lists.fedoraproject.org/pipermail/package-announce/2011-July/063118.html
http://lists.apple.com/archives/Security-announce/2011//Oct/msg00003.html