Multiple researchers have discovered a vulnerability in the way the Intel processor designs have implemented speculative execution of instructions in combination with handling of page-faults. This flaw could allow an attacker controlling an unprivileged process to read memory from arbitrary addresses, including from the kernel and all other processes running on the system or cross guest/host boundaries to read host memory. To fully resolve these vulnerabilities it is also necessary to install updated CPU microcode . Common server class CPUs are covered in the update released as DSA 4273-1.