A flaw was found in the Linux kernel's key management system where it was possible for an attacker to escalate privileges or crash the machine. If a user key gets negatively instantiated, an error code is cached in the payload area. A negatively instantiated key may be then be positively instantiated by updating it with valid data. However, the ->update key type method must be aware that the error code may be there.
Find out more about CVE-2015-8539 from the
MITRE CVE dictionary dictionary and
This issue does not affect the Linux kernels as shipped with Red Hat Enterprise Linux 4 and 5. This issue does affect the kernels shipped with Red Hat Enterprise Linux 6, 7, MRG-2 and realtime kernels and plans to be addressed in a future update.