Multiple stack-based buffer overflows in the Sieve plugin in Dovecot 1.0 before 1.0.4 and 1.1 before 1.1.7, as derived from Cyrus libsieve, allow context-dependent attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted SIEVE script, as demonstrated by forwarding an e-mail message to a large number of recipients, a different vulnerability than CVE-2009-2632.
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.