CVE-2018-12891 Affecting xen package, versions <4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published11 Jul 2018
- disclosed2 Jul 2018
Introduced: 2 Jul 2018
CVE-2018-12891 (opens in a new tab)How to fix?
Upgrade Debian:10 xen to version 4.8.3+xsa267+shim4.10.1+xsa267-1+deb9u9 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream xen package and not the xen package as distributed by Debian.
See How to fix? for Debian:10 relevant fixed versions and status.
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.
References
- https://security-tracker.debian.org/tracker/CVE-2018-12891
- https://support.citrix.com/article/CTX235748
- http://xenbits.xen.org/xsa/advisory-264.html
- https://www.debian.org/security/2018/dsa-4236
- https://lists.debian.org/debian-lts-announce/2018/11/msg00013.html
- https://security.gentoo.org/glsa/201810-06
- http://www.openwall.com/lists/oss-security/2018/06/27/10
- http://www.securityfocus.com/bid/104570
- http://www.securitytracker.com/id/1041201
- http://people.ubuntu.com/~ubuntu-security/cve/CVE-2018-12891