VERITAS Backup Exec 9.0 through 10.0 for Windows Servers, and 9.0.4019 through 9.1.307 for Netware, allows remote attackers to cause a denial of service (Remote Agent crash) via (1) a crafted packet in NDMLSRVR.DLL or (2) a request packet with an invalid (non-0) "Error Status" value, which triggers a null dereference.