Format string vulnerability in SMTP service for WebEasyMail 3.4.2.2 and earlier allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via format strings in SMTP requests.

The POP3 service for WebEasyMail 3.4.2.2 and earlier generates diffferent error messages for valid and invalid usernames during authentication, which makes it easier for remote attackers to conduct brute force attacks.