The ParseValue function in lexer.c in tidy before 4.9.31 allows remote attackers to cause a denial of service (crash) via vectors involving multiple whitespace characters before an empty href, which triggers a large memory allocation.Referenceshttp://www.securitytracker.com/id/1033703http://www.openwall.com/lists/oss-security/2015/07/13/7https://support.apple.com/HT205212http://lists.apple.com/archives/security-announce/2015/Sep/msg00008.htmlhttp://www.openwall.com/lists/oss-security/2015/06/04/2http://www.ubuntu.com/usn/USN-2695-1https://support.apple.com/HT205267http://www.debian.org/security/2015/dsa-3309http://lists.apple.com/archives/security-announce/2015/Sep/msg00005.htmlhttps://github.com/htacg/tidy-html5/issues/217#issuecomment-108565501https://support.apple.com/HT205213http://www.securityfocus.com/bid/75037http://lists.apple.com/archives/security-announce/2015/Sep/msg00001.htmlhttp://www.openwall.com/lists/oss-security/2015/07/15/3