CVE-2018-12891

Impact:
Moderate
Public Date:
2018-06-27
CWE:
CWE-358
Bugzilla:
1590985: CVE-2018-12891 xen: preemption checks bypassed in x86 PV MM handling (XSA-264)

The MITRE CVE dictionary describes this issue as:

An issue was discovered in Xen through 4.10.x. Certain PV MMU operations may take a long time to process. For that reason Xen explicitly checks for the need to preempt the current vCPU at certain points. A few rarely taken code paths did bypass such checks. By suitably enforcing the conditions through its own page table contents, a malicious guest may cause such bypasses to be used for an unbounded number of iterations. A malicious or buggy PV guest may cause a Denial of Service (DoS) affecting the entire host. Specifically, it may prevent use of a physical CPU for an indeterminate period of time. All Xen versions from 3.4 onwards are vulnerable. Xen versions 3.3 and earlier are vulnerable to an even wider class of attacks, due to them lacking preemption checks altogether in the affected code paths. Only x86 systems are affected. ARM systems are not affected. Only multi-vCPU x86 PV guests can leverage the vulnerability. x86 HVM or PVH guests as well as x86 single-vCPU PV ones cannot leverage the vulnerability.

Find out more about CVE-2018-12891 from the MITRE CVE dictionary dictionary and NIST NVD.

CVSS v3 metrics

NOTE: The following CVSS v3 metrics and score provided are preliminary and subject to review.

CVSS3 Base Score 6.5
CVSS3 Base Metrics CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Changed
Confidentiality None
Integrity Impact None
Availability Impact High

Affected Packages State

Platform Package State
Red Hat Enterprise Linux 5 xen Will not fix

Acknowledgements

Red Hat would like to thank the Xen project for reporting this issue. Upstream acknowledges Jan Beulich (SUSE) as the original reporter.

Last Modified

CVE description copyright © 2017, The MITRE Corporation

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