This update is based on upstream 5.5.6 and fixes at least the following security vulnerability:
A flaw was found in the way KVM hypervisor handled instruction emulation for the L2 guest when nested(=1) virtualization is enabled. In the instruction emulation, the L2 guest could trick the L0 hypervisor into accessing sensitive bits of the L1 hypervisor. An L2 guest could use this flaw to potentially access information of the L1 hypervisor (CVE-2020-2732).
Other additional fixes in this update: - a fix for broken radeon on 32bit (mga#26237) - broken iwlwifi for some (mga#26248) - a bugfix for pipe optimization backported in the 5.5.4 update
For other upstream fixes in this update, see the referenced changelogs.