Public Date:
813428: CVE-2012-0217 kernel: x86-64: avoid sysret to non-canonical address
It was found that the Xen hypervisor implementation as shipped with Red Hat Enterprise Linux 5 did not properly restrict the syscall return addresses in the sysret return path to canonical addresses. An unprivileged user in a 64-bit para-virtualized guest, that is running on a 64-bit host that has an Intel CPU, could use this flaw to crash the host or, potentially, escalate their privileges, allowing them to execute arbitrary code at the hypervisor level.

Find out more about CVE-2012-0217 from the MITRE CVE dictionary dictionary and NIST NVD.


This issue did not affect the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 5 and 6, and Red Hat Enterprise MRG, as those versions have a guard page between the end of the user-mode accessible virtual address space and the beginning of the non-canonical area due to CVE-2005-1764 fix, and hardened system call handler due to CVE-2006-0744 fix. This issue did affect the versions of Xen hypervisor as shipped with Red Hat Enterprise Linux 5. A kernel-xen update for Red Hat Enterprise Linux 5 is available to address this flaw.

CVSS v2 metrics

NOTE: The following CVSS v2 metrics and score provided are preliminary and subject to review.

Base Score 7.9
Base Metrics AV:A/AC:M/Au:N/C:C/I:C/A:C
Access Vector Adjacent Network
Access Complexity Medium
Authentication None
Confidentiality Impact Complete
Integrity Impact Complete
Availability Impact Complete

Find out more about Red Hat support for the Common Vulnerability Scoring System (CVSS).

Red Hat Security Errata

Platform Errata Release Date
Red Hat Enterprise Linux EUS (v. 5.6 server) (kernel) RHSA-2012:0720 2012-06-12
Red Hat Enterprise Linux version 5 (kernel) RHSA-2012:0721 2012-06-12

Affected Packages State

Platform Package State
Red Hat Enterprise Linux 5 kernel-xen Affected
Red Hat Enterprise Linux 6 kernel Not affected
Red Hat Enterprise Linux EUS (v. 5.6 server) kernel-xen Affected


Red Hat would like to thank the Xen project for reporting this issue. Upstream acknowledges Rafal Wojtczuk as the original reporter.