CVE-1999-1150: Livingston Portmaster Portmaster

High severity, CVSS 7.5. EPSS: 1.4% chance of exploitation in the next 30 days.

Livingston Portmaster routers running ComOS use the same initial sequence number (ISN) for TCP connections, which allows remote attackers to conduct spoofing and hijack TCP sessions.

Affected products

• Livingston Portmaster Portmaster: version initial only

Published 1998-06-30. Last modified 2026-06-16.