Side channel execution mitigations were added to QEMU.
Ken Johnson and Jann Horn independently discovered that microprocessors utilizing speculative execution of a memory read may allow unauthorized memory reads via sidechannel attacks. An attacker in the guest could use this to expose sensitive guest information, including kernel memory. This update allows QEMU to expose new CPU features added by microcode updates to guests on amd64 and i386.
21 May 2018
A security issue affects these releases of Ubuntu and its derivatives:
Side channel execution mitigations were added to QEMU.
Ken Johnson and Jann Horn independently discovered that microprocessors utilizing speculative execution of a memory read may allow unauthorized memory reads via sidechannel attacks. An attacker in the guest could use this to expose sensitive guest information, including kernel memory. This update allows QEMU to expose new CPU features added by microcode updates to guests on amd64 and i386.
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
After a standard system update you need to restart all QEMU virtual machines to make all the necessary changes.
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