A flaw was found in Dovecot. Processing a large number of address headers (From, To, Cc, Bcc, etc) can be excessively CPU intensive. This flaw allows a remote attacker to trigger a denial of service.

A security issue was found in Dovecot. Very large headers can lead to resource exhaustion when parsing messages. The message-parser normally reads reasonably sized chunks of the message. However, when it feeds them to the message-header-parser, it starts building up a "full_value" buffer out of the smaller chunks. The full_value buffer has no size limit so large headers can cause large memory usage. This issue occurs whether it is a single long header line or a single header split into multiple lines.