Buffer overflows in Fetchmail 6.0.0 and earlier allow remote attackers to cause a denial of service (crash) or execute arbitrary code via (1) long headers that are not properly processed by the readheaders function, or (2) via long Received: headers, which are not properly parsed by the parse_received function.

fetchmail email client before 5.9.10 does not properly limit the maximum number of messages available, which allows a remote IMAP server to overwrite memory via a message count that exceeds the boundaries of an array.