poppassd_pam is a PAM-enabled server for changing system passwords that can be used to change POP server passwords.
Gentoo Linux developer Marcus Hanwell discovered that poppassd_pam did not check that the old password was valid before changing passwords. Our investigation revealed that poppassd_pam did not call pam_authenticate before calling pam_chauthtok.
A remote attacker could change the system password of any user, including root. This leads to a complete compromise of the POP accounts, and may also lead to a complete root compromise of the affected server, if it also provides shell access authenticated using system passwords.
There is no known workaround at this time.
All poppassd_pam users should migrate to the new package called poppassd_ceti:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-mail/poppassd_ceti-1.8.4"
Note: Portage will automatically replace the poppassd_pam package by the poppassd_ceti package.