Debian: DSA-3729-1: xen security update

    Date07 Dec 2016
    CategoryDebian
    42
    Posted ByLinuxSecurity Advisories
    Multiple vulnerabilities have been discovered in the Xen hypervisor. The Common Vulnerabilities and Exposures project identifies the following problems:
    
    - -------------------------------------------------------------------------
    Debian Security Advisory DSA-3729-1                   This email address is being protected from spambots. You need JavaScript enabled to view it.
    https://www.debian.org/security/                     Salvatore Bonaccorso
    December 07, 2016                     https://www.debian.org/security/faq
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    Package        : xen
    CVE ID         : CVE-2016-7777 CVE-2016-9379 CVE-2016-9380 CVE-2016-9382
                     CVE-2016-9383 CVE-2016-9385 CVE-2016-9386
    Debian Bug     : 845663 845664 845665 845668 845670
    
    Multiple vulnerabilities have been discovered in the Xen hypervisor. The
    Common Vulnerabilities and Exposures project identifies the following
    problems:
    
    CVE-2016-7777 (XSA-190)
    
        Jan Beulich from SUSE discovered that Xen does not properly honor
        CR0.TS and CR0.EM for x86 HVM guests, potentially allowing guest
        users to read or modify FPU, MMX, or XMM register state information
        belonging to arbitrary tasks on the guest by modifying an
        instruction while the hypervisor is preparing to emulate it.
    
    CVE-2016-9379, CVE-2016-9380 (XSA-198)
    
        Daniel Richman and Gabor Szarka of the Cambridge University
        Student-Run Computing Facility discovered that pygrub, the boot
        loader emulator, fails to quote (or sanity check) its results when
        reporting them to its caller. A malicious guest administrator can
        take advantage of this flaw to cause an information leak or denial
        of service.
    
    CVE-2016-9382 (XSA-192)
    
        Jan Beulich of SUSE discovered that Xen does not properly handle x86
        task switches to VM86 mode. A unprivileged guest process can take
        advantage of this flaw to crash the guest or, escalate its
        privileges to that of the guest operating system.
    
    CVE-2016-9383 (XSA-195)
    
        George Dunlap of Citrix discovered that the Xen x86 64-bit bit test
        instruction emulation is broken. A malicious guest can take
        advantage of this flaw to modify arbitrary memory, allowing for
        arbitrary code execution, denial of service (host crash), or
        information leaks.
    
    CVE-2016-9385 (XSA-193)
    
        Andrew Cooper of Citrix discovered that Xen's x86 segment base write
        emulation lacks canonical address checks. A malicious guest
        administrator can take advantage of this flaw to crash the host,
        leading to a denial of service.
    
    CVE-2016-9386 (XSA-191)
    
        Andrew Cooper of Citrix discovered that x86 null segments are not
        always treated as unusable. An unprivileged guest user program
        may be able to elevate its privilege to that of the guest
        operating system.
    
    For the stable distribution (jessie), these problems have been fixed in
    version 4.4.1-9+deb8u8.
    
    We recommend that you upgrade your xen packages.
    
    Further information about Debian Security Advisories, how to apply
    these updates to your system and frequently asked questions can be
    found at: https://www.debian.org/security/
    
    Mailing list: This email address is being protected from spambots. You need JavaScript enabled to view it.
    
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