Roundcube is a browser-based multilingual IMAP client with an application-like user interface.
A vulnerability in steps/utils/save_pref.inc allows remote attackers to use the _session parameter to change configuration settings.
A remote attacker could possibly execute arbitrary code with the privileges of the process, inject SQL code, or read arbitrary files.
There is no known workaround at this time.
All Roundcube 0.9 users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=mail-client/roundcube-0.9.5"
All Roundcube 0.8 users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=mail-client/roundcube-0.8.7"