Format string vulnerability in the incputerror function in src/inc.c in Sylpheed 2.4.4, and Sylpheed-Claws (Claws Mail) 1.9.100 and 2.10.0, allows remote POP3 servers to execute arbitrary code via format string specifiers in crafted replies.

Buffer overflow in Sylpheed before 1.0.3 and other versions before 1.9.5 allows remote attackers to execute arbitrary code via an e-mail message with certain headers containing non-ASCII characters that are not properly handled when the user replies to the message.

Format string vulnerability in sendmessage.c for Sylpheed-claws 0.9.4 through 0.9.6 allows remote SMTP servers to cause a denial of service (crash) in sylpheed via format strings in an error message.

Sylpheed-Claws before 2.2.2 and Sylpheed before 2.2.6 allow remote attackers to bypass the URI check functionality and makes it easier to conduct phishing attacks via a URI that begins with a space character.