An flaw was discovered in the Linux kernel’s CIFS client implementation. While issuing an SMB2_write, a value can be used after it was intended to be freed when CIFS function tracing is enabled. Even though the data is used after being freed, using it to for privilege escalation does not seem possible.

Mitigation

As the CIFS module will be auto-loaded when required, its use can be disabled by preventing the module from loading with the following instructions:

echo "install cifs /bin/true" >> /etc/modprobe.d/disable-cifs.conf

The system will need to be restarted if the CIFS modules are loaded. In most circumstances, the CIFS kernel modules will be unable to be unloaded while any network interfaces are active and the protocol is in use.

If you need further assistance, see KCS article <https://access.redhat.com/solutions/41278&gt; or contact Red Hat Global Support Services.