documentation/docs/admin-guide/security/mitigation_dirty_frag.md

Mitigation Dirty Frag

Following commands can be used to disable the vulnerable feature:

modprobe -r esp4 esp6 rxrpc
cat > /etc/modprobe.d/mitigation-dirtyfrag.conf <<'EOF'
install esp4 /bin/false
install esp6 /bin/false
install rxrpc /bin/false
blacklist esp4
blacklist esp6
blacklist rxrpc
EOF

The warning

modprobe: FATAL: Module rxrpc not found.

is fine

Source: https://github.com/V4bel/dirtyfrag