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.
Exploitability
AV:LAC:LPR:LUI:NScope
S:UImpact
C:HI:HA:H7.8/CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H