In FreeBSD 12.1-STABLE before r356035, 12.1-RELEASE before 12.1-RELEASE-p4, 11.3-STABLE before r356036, and 11.3-RELEASE before 11.3-RELEASE-p8, incomplete packet data validation may result in accessing out-of-bounds memory leading to a kernel panic or other unpredictable results.
https://security.netapp.com/advisory/ntap-20200511-0002/
https://security.FreeBSD.org/advisories/FreeBSD-SA-20:10.ipfw.asc