Arch Linux: Access restriction bypass (CVE-2017-5754)

An industry-wide issue was found in the way many modern microprocessor designs have implemented speculative execution of instructions (a commonly used performance optimization).
This variant ("Rogue Data Load") relies on the fact that, on impacted microprocessors, during speculative execution of instruction permission faults, exception generation triggered by a faulting access is suppressed until the retirement of the whole instruction block. In a combination with the fact that memory accesses may populate the cache even when the block is being dropped and never committed (executed), an unprivileged local attacker could use this flaw to read memory from arbitrary addresses, including privileged (kernel space) and all other processes running on the system by conducting targeted cache side-channel attacks.