Buffer overflow in (1) lprintf and (2) cprintf in sysdep.c of Citadel/UX 5.90 and earlier allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via attacks such as a long HELO command to the SMTP server.

Format string vulnerability in the lprintf function in Citadel/UX 6.27 and earlier allows remote attackers to execute arbitrary code via format string specifiers sent to the server.

Buffer overflow in Citadel/UX 6.23 and earlier allows remote attackers to cause a denial of service via a long username.

Citadel/UX 5.00 through 6.14 installs the database directory and files with world-read permissions, which could allow local users to bypass access controls and read unauthorized messages.