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.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-17470
Reference (s):
- http://fnet.sourceforge.net/manual/fnet_history.html
- https://us-cert.cisa.gov/ics/advisories/icsa-20-343-01
- https://www.kb.cert.org/vuls/id/815128