bitcoind and Bitcoin-Qt 0.8.x before 0.8.1 do not enforce a certain block protocol rule, which allows remote attackers to bypass intended access restrictions and conduct double-spending attacks via a large block that triggers incorrect Berkeley DB locking in older product versions.
Unspecified vulnerability in bitcoind and Bitcoin-Qt 0.8.x allows remote attackers to cause a denial of service (memory consumption) via a large amount of tx message data.