nss_ldap is a Name Service Switch module which allows 'passwd', 'group' and 'host' database information to be pulled from LDAP.
Josh Burley reported that nss_ldap does not properly handle the LDAP connections due to a race condition that can be triggered by multi-threaded applications using nss_ldap, which might lead to requested data being returned to a wrong process.
Remote attackers could exploit this race condition by sending queries to a vulnerable server using nss_ldap, possibly leading to theft of user credentials or information disclosure (e.g. Dovecot returning wrong mailbox contents).
There is no known workaround at this time.
All nss_ldap users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=sys-auth/nss_ldap-258"