Multiple heap-based buffer overflows in the XML manifest encryption tag parsing functionality in OpenOffice.org and LibreOffice before 3.5.5 allow remote attackers to cause a denial of service and possibly execute arbitrary code via a crafted Open Document Text (.odt) file with (1) a child tag within an incorrect parent tag, (2) duplicate tags, or (3) a Base64 ChecksumAttribute whose length is not evenly divisible by four.