CVE-2012-0217
Description
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.
Statement
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.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v2 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.9 | 7.2 | N/A |
| Attack Vector | Adjacent Network | Local | N/A |
| Access Complexity | Medium | Low | N/A |
| Authentication | None | None | N/A |
| Confidentiality Impact | Complete | Complete | N/A |
| Integrity Impact | Complete | Complete | N/A |
| Availability Impact | Complete | Complete | N/A |
Vector
Red Hat: AV:A/AC:M/Au:N/C:C/I:C/A:C
NVD: AV:L/AC:L/Au:N/C:C/I:C/A:C
Acknowledgements
Red Hat would like to thank Xen project for reporting this issue. Upstream acknowledges Rafal Wojtczuk as the original reporter.
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