Race condition in the store_int_with_restart() function in arch/x86/kernel/cpu/mcheck/mce.c in the Linux kernel allows local users to cause a denial of service (panic) by leveraging root access to write to the check_interval file in a /sys/devices/system/machinecheck/machinecheck<cpu number> directory.
An upsteam patch:
Created kernel tracking bugs for this issue:
Affects: fedora-all [bug 1553918]
kernel-4.15.9-200.fc26 has been pushed to the Fedora 26 stable repository. If problems still persist, please make note of it in this bug report.
Since only root can write to the mentioned sysfs variables, the issue is not a security flaw.