Ubuntu Security Notice 3655-2 - USN-3655-1 fixed vulnerabilities and added mitigations in the Linux kernel for Ubuntu 14.04 LTS. This update provides the corresponding updates for the Linux Hardware Enablement kernel from Ubuntu 14.04 LTS for Ubuntu 12.04 ESM. Jann Horn and Ken Johnson discovered that microprocessors utilizing speculative execution of a memory read may allow unauthorized memory reads via a sidechannel attack. This flaw is known as Spectre Variant 4. A local attacker could use this to expose sensitive information, including kernel memory. Various other issues were also addressed.
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