Last week a serious Local Privilege Escalation vulnerability was found in the Linux kernel, its called Dirty COW. The term COW stands for Copy-On-Write. A race condition was found on kernel's memory subsystem that handles the copy-on-write breakage of private read-only memory mappings. Thus an unprivileged local user can use this flaw to gain escalated access.
It affects all RHEL kernels used in 7.x, 6.x and 5.x.
We can see kernel patches for RHEL 7 and 6 were released by Red Hat at the time of writing this. We hope patches for rest of the versions will be released soon.