The login form in Roundcube Webmail before 0.5.1 does not properly handle a correctly authenticated but unintended login attempt, which makes it easier for remote authenticated users to obtain sensitive information by arranging for a victim to login to the attacker's account and then compose an e-mail message, related to a "login CSRF" issue.

Cross-site scripting (XSS) vulnerability in NikoSoft WebMail before 0.11.0 allows remote attackers to inject arbitrary web script or HTML via unknown vectors.

Multiple buffer overflows in (1) iso2022jp.c or (2) shiftjis.c for Courier-IMAP before 3.0.0, Courier before 0.45, and SqWebMail before 4.0.0 may allow remote attackers to execute arbitrary code "when Unicode character is out of BMP range."