Xen VCPU denial of service

xen-vcpu-dos (80022) The risk level is classified as MediumMedium Risk


Xen is vulnerable to a denial of service, caused by an error when handling the VCPU deadline. A local attacker on a guest operating system could exploit this vulnerability to cause the system to enter into an infinite loop and crash.


Base Score: 2.1
  Access Vector: Local
  Access Complexity: Low
  Authentication: None
  Confidentiality Impact: None
  Integrity Impact: None
  Availability Impact: Partial
Temporal Score: 1.6
  Exploitability: Unproven
  Remediation Level: Official-Fix
  Report Confidence: Confirmed


Denial of Service


Refer to Xen Security Advisory 20 (CVE-2012-4535) for patch, upgrade or suggested workaround information. See References.

For other distributions:
Apply the appropriate update for your system. See References.


  • CTX135458: Citrix XenServer Multiple Security Updates .
  • Xen Security Advisory 20 (CVE-2012-4535): Timer overflow DoS vulnerability.
  • BID-56498: Xen Multiple Denial of Service Vulnerabilities
  • CVE-2012-4535: Xen 3.4 through 4.2, and possibly earlier versions, allows local guest OS administrators to cause a denial of service (Xen infinite loop and physical CPU consumption) by setting a VCPU with an inappropriate deadline.
  • DSA-2582: xen -- several vulnerabilities
  • RHSA-2012-1540: Important: kernel security, bug fix, and enhancement update
  • SA51200: Xen Multiple Denial of Service Vulnerabilities
  • SA51214: Citrix XenServer Multiple Denial of Service Vulnerabilities

Platforms Affected:

  • Citrix XenServer 5.0
  • Citrix XenServer 5.5
  • Citrix XenServer 5.6
  • Citrix XenServer 6.0
  • Citrix XenServer 6.1
  • RedHat Enterprise Linux 5 Client
  • RedHat Enterprise Linux 5
  • XenSource Xen 3.0
  • XenSource Xen 4.1
  • XenSource Xen 4.1.1
  • XenSource Xen 4.1.2


Nov 13, 2012

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