Bug 1891096 (CVE-2020-27672) - CVE-2020-27672 xen: x86: race condition in Xen mapping code (XSA-345)
Summary: CVE-2020-27672 xen: x86: race condition in Xen mapping code (XSA-345)
Alias: CVE-2020-27672
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1891097
Blocks: 1891100
TreeView+ depends on / blocked
Reported: 2020-10-23 19:00 UTC by Guilherme de Almeida Suckevicz
Modified: 2021-02-16 19:01 UTC (History)
25 users (show)

Fixed In Version:
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Doc Text:
A race condition flaw was found in the Xen code responsible for handling the updating of the hypervisor's own page tables. This flaw allows a malicious guest to cause a denial of service, host data corruption, or potential privilege escalation. The highest threat from this vulnerability is to confidentiality, integrity as well as system availability.
Clone Of:
Last Closed: 2020-11-02 20:21:30 UTC

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Description Guilherme de Almeida Suckevicz 2020-10-23 19:00:15 UTC
An issue was discovered in versions of Xen from at least 3.2 onward, allowing x86 guest OS users to cause a host OS denial of service, achieve data corruption, or possibly gain privileges by exploiting a race condition that leads to a use-after-free involving 2MiB and 1GiB superpages.

Comment 1 Guilherme de Almeida Suckevicz 2020-10-23 19:00:37 UTC
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1891097]

Comment 2 Mauro Matteo Cascella 2020-11-02 14:38:25 UTC

Name: the Xen project

Comment 3 Mauro Matteo Cascella 2020-11-02 14:39:46 UTC
External References:


Comment 5 Product Security DevOps Team 2020-11-02 20:21:30 UTC
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):


Comment 6 Mauro Matteo Cascella 2020-11-03 13:13:41 UTC

All Xen versions from 3.2 onwards are vulnerable. Red Hat Enterprise Linux 5 is not affected by this flaw, as it shipped with an older version of Xen.

Comment 7 Mauro Matteo Cascella 2020-11-03 13:13:44 UTC

Running all guests in HVM or PVH mode, in each case with HAP enabled, will prevent those guests from exploiting the vulnerability.

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