Ubuntu Security Notice 2516-1 - A flaw was discovered in the Kernel Virtual Machine's (KVM) emulation of the SYSTENTER instruction when the guest OS does not initialize the SYSENTER MSRs. A guest OS user could exploit this flaw to cause a denial of service of the guest OS (crash) or potentially gain privileges on the guest OS. Andy Lutomirski discovered an information leak in the Linux kernel's Thread Local Storage (TLS) implementation allowing users to bypass the espfix to obtain information that could be used to bypass the Address Space Layout Randomization (ASLR) protection mechanism. A local user could exploit this flaw to obtain potentially sensitive information from kernel memory. Various other issues were also addressed.
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