A use-after-free issue was found in the way the Linux kernel's KVM hypervisor processed posted interrupts when nested(=1) virtualization is enabled. In nestedgetvmcs12pages(), in case of an error while processing posted interrupt address, it unmaps the 'pidescpage' without resetting 'pidesc' descriptor address, which is later used in pitestandclearon(). A guest user/process could use this flaw to crash the host kernel resulting in DoS or potentially gain privileged access to a system. Kernel versions before 4.14.91 and before 4.19.13 are vulnerable.