The HTTPAuthorized function in bitcoinrpc.cpp in bitcoind 0.8.1 provides information about authentication failure upon detecting the first incorrect byte of a password, which makes it easier for remote attackers to determine passwords via a timing side-channel attack.

The Bloom Filter implementation in bitcoind and Bitcoin-Qt 0.8.x before 0.8.4rc1 allows remote attackers to cause a denial of service (divide-by-zero error and daemon crash) via a crafted sequence of messages.