CVE-2020-27633: Butok Fnet

Critical severity, CVSS 9.1. EPSS: 0.9% chance of exploitation in the next 30 days.

In FNET 4.6.3, TCP ISNs are improperly random.

Affected products

• Butok Fnet: version 4.6.3 only

Published 2023-10-10. Last modified 2026-06-17.