kernel/ucount.c in the Linux kernel 5.14 through 5.16.4, when unprivileged user namespaces are enabled, allows a use-after-free and privilege escalation because a ucounts object can outlive its namespace.
5.13.0-19.195.15.0-17.175.15.0-18.185.15.0-22.224.13.0-16.195.3.0-18.195.3.0-24.265.4.0-9.126.5.0-9.95.13.0-1005.64.15.0-1001.15.3.0-1003.35.3.0-1008.95.3.0-1009.105.3.0-1010.115.4.0-1005.56.5.0-1008.85.0.0-1021.24~18.04.15.0.0-1022.25~18.04.15.0.0-1023.26~18.04.15.0.0-1024.27~18.04.15.0.0-1025.285.0.0-1027.305.11.0-1009.9~20.04.2Exploitability
AV:LAC:LPR:LUI:NScope
S:UImpact
C:HI:HA:HCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H