Horde IMP provides a web-based access to IMAP and POP3 mailboxes.
Ulf Harnhammar, Secunia Research discovered that the "frame" and "frameset" HTML tags are not properly filtered out. He also reported that certain HTTP requests are executed without being checked.
A remote attacker could entice a user to open a specially crafted HTML e-mail, possibly resulting in the deletion of arbitrary e-mail messages.
There is no known workaround at this time.
All Horde IMP users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=www-apps/horde-imp-4.1.6"