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.