Free and open source webmail software for the masses, written in PHP.
Roundcube, when no SMTP server is configured and the sendmail program is enabled, does not properly restrict the use of custom envelope-from addresses on the sendmail command line.
An authenticated remote attacker could possibly execute arbitrary code with the privileges of the process, or cause a Denial of Service condition.
Don’t use a MTA (Mail Transfer Agent) in conjunction with Roundcube which implements sendmail’s “-O” or “-X” parameter, or configure Roundcube to use a SMTP server as recommended by upstream.
All Roundcube users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=mail-client/roundcube-1.2.3"