hso_free_net_device in drivers/net/usb/hso.c in the Linux kernel through 5.13.4 calls unregister_netdev without checking for the NETREG_REGISTERED state, leading to a use-after-free and a double free. CREATE(Triage):(User=admin) CVE-2021-37159 (https://nvd.nist.gov/vuln/detail/CVE-2021-37159)