CVE-2020-17470: Butok Fnet

Medium severity, CVSS 5.3. EPSS: 2.1% chance of exploitation in the next 30 days.

An issue was discovered in FNET through 4.6.4. The code that initializes the DNS client interface structure does not set sufficiently random transaction IDs (they are always set to 1 in _fnet_dns_poll in fnet_dns.c). This significantly simplifies DNS cache poisoning attacks.

Affected products

• Butok Fnet: up to and including 4.6.4

Published 2020-12-11. Last modified 2026-06-17.