Apache Santuario XML Security for C++ (aka xml-security-c) before 1.7.1 does not properly validate length values, which allows remote attackers to cause a denial of service or bypass the CVE-2009-0217 protection mechanism and spoof a signature via crafted length values to the (1) compareBase64StringToRaw, (2) DSIGAlgorithmHandlerDefault, or (3) DSIGAlgorithmHandlerDefault::verify functions.