It indicates a possible exploit of a buffer overflow vulnerability in Citadel/UX.
This problem occurs due to insufficient bounds checking when processing 'USER' command arguments.
Citadel/UX Citadel/UX 6.23
Citadel/UX Citadel/UX 6.0 8
Citadel/UX Citadel/UX 6.0 7
Citadel/UX Citadel/UX 5.91
Citadel/UX Citadel/UX 5.90
Denial of service
It is reported that the vendor has addressed this issue; the fix exists in the CVS tree.