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Vulnerability of Xen: denial of service via Linux High Frequency Events

Synthesis of the vulnerability 

An attacker, inside a guest system, can trigger a fatal error via Linux High Frequency Events of Xen, in order to trigger a denial of service on the host system.
Vulnerable products: XenServer, Linux, openSUSE Leap, SUSE Linux Enterprise Desktop, SLES.
Severity of this weakness: 1/4.
Creation date: 20/10/2020.
Références of this bulletin: CERTFR-2020-AVI-657, CERTFR-2020-AVI-693, CERTFR-2020-AVI-741, CERTFR-2020-AVI-764, CERTFR-2020-AVI-769, CTX284874, CVE-2020-27673, openSUSE-SU-2020:1783-1, openSUSE-SU-2020:1844-1, SUSE-SU-2020:3049-1, SUSE-SU-2020:3050-1, SUSE-SU-2020:3051-1, SUSE-SU-2020:3052-1, SUSE-SU-2020:3088-1, SUSE-SU-2020:3272-1, SUSE-SU-2020:3281-1, SUSE-SU-2020:3491-1, SUSE-SU-2020:3532-1, SUSE-SU-2020:3544-1, VIGILANCE-VUL-33630, XSA-332.

Description of the vulnerability 

An attacker, inside a guest system, can trigger a fatal error via Linux High Frequency Events of Xen, in order to trigger a denial of service on the host system.
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This computer weakness impacts software or systems such as XenServer, Linux, openSUSE Leap, SUSE Linux Enterprise Desktop, SLES.

Our Vigil@nce team determined that the severity of this vulnerability note is low.

The trust level is of type confirmed by the editor, with an origin of user shell.

An attacker with a expert ability can exploit this cybersecurity threat.

Solutions for this threat 

Linux kernel: version 5.9.5.
The version 5.9.5 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v5.x/

Linux kernel: version 5.4.75.
The version 5.4.75 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v5.x/

Linux kernel: version 4.19.155.
The version 4.19.155 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v4.x/

Linux kernel: patch for Xen Linux High Frequency Events.
A patch is available:
  http://xenbits.xen.org/xsa/xsa332-linux-01.patch
  http://xenbits.xen.org/xsa/xsa332-linux-02.patch
  http://xenbits.xen.org/xsa/xsa332-linux-03.patch
  http://xenbits.xen.org/xsa/xsa332-linux-04.patch
  http://xenbits.xen.org/xsa/xsa332-linux-05.patch
  http://xenbits.xen.org/xsa/xsa332-linux-06.patch
  http://xenbits.xen.org/xsa/xsa332-linux-07.patch
  http://xenbits.xen.org/xsa/xsa332-linux-08.patch
  http://xenbits.xen.org/xsa/xsa332-linux-09.patch
  http://xenbits.xen.org/xsa/xsa332-linux-10.patch
  http://xenbits.xen.org/xsa/xsa332-linux-11.patch
  http://xenbits.xen.org/xsa/xsa332-linux-12.patch

Citrix Hypervisor, XenServer: patch.
A patch is available:
  Citrix Hypervisor 8.2 LTSR: https://support.citrix.com/article/CTX285310 + https://support.citrix.com/article/CTX285316
  Citrix Hypervisor 8.1: https://support.citrix.com/article/CTX285309 + https://support.citrix.com/article/CTX285315
  Citrix XenServer 7.1 LTSR CU2: https://support.citrix.com/article/CTX285308 + https://support.citrix.com/article/CTX285314
  Citrix XenServer 7.0: https://support.citrix.com/article/CTX285307 + https://support.citrix.com/article/CTX285312

openSUSE Leap 15.1: new xen packages.
New packages are available:
  openSUSE Leap 15.1: xen 4.12.3_10-lp151.2.27.1

openSUSE Leap 15.2: new xen packages.
New packages are available:
  openSUSE Leap 15.2: xen 4.13.1_10-lp152.2.12.1

SUSE LE 12 SP4: new kernel-default packages.
New packages are available:
  SUSE LE 12 SP4: kernel-default 4.12.14-95.65.1

SUSE LE 12 SP4: new xen packages.
New packages are available:
  SUSE LE 12 SP4: xen 4.11.4_10-2.39.2

SUSE LE 12 SP5: new kernel-azure packages.
New packages are available:
  SUSE LE 12 SP5: kernel-azure 4.12.14-16.34.1

SUSE LE 12 SP5: new xen packages.
New packages are available:
  SUSE LE 12 SP5: xen 4.12.3_10-3.27.1

SUSE LE 15: new kernel packages.
New packages are available:
  SUSE LE 15 RTM: kernel-default-livepatch 4.12.14-150.63.1, kernel-livepatch 4_12_14-150_63-default-1-1.5.1

SUSE LE 15: new xen packages.
New packages are available:
  SUSE LE 15 RTM: xen 4.10.4_18-3.44.1
  SUSE LE 15 SP1: xen 4.12.3_10-3.31.1
  SUSE LE 15 SP2: xen 4.13.1_10-3.13.1

SUSE LE 15 SP1: new kernel packages.
New packages are available:
  SUSE LE 15 SP1: kernel 4.12.14-197.67.1

SUSE LE 15 SP2: new kernel-azure packages (24/11/2020).
New packages are available:
  SUSE LE 15 SP2: kernel-azure 5.3.18-18.24.1
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