base_sock_create in drivers/isdn/mISDN/socket.c in the AF_ISDN network module in the Linux kernel through 5.3.2 does not enforce CAP_NET_RAW, which means that unprivileged users can create a raw socket, aka CID-b91ee4aa2a21.
Exploitability
AV:LAC:LPR:LUI:NScope
S:UImpact
C:NI:LA:N3.3/CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N