An issue was discovered in FNET through 4.6.4. The code for processing the hop-by-hop header (in the IPv6 extension headers) doesn't check for a valid length of an extension header, and therefore an out-of-bounds read can occur in _fnet_ip6_ext_header_handler_options in fnet_ip6.c, leading to Denial-of-Service.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-17468
• https://us-cert.cisa.gov/ics/advisories/icsa-20-343-01
• https://www.kb.cert.org/vuls/id/815128
• http://fnet.sourceforge.net/manual/fnet_history.html