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CVE-2020-25604

Published: 23 September 2020

An issue was discovered in Xen through 4.14.x. There is a race condition when migrating timers between x86 HVM vCPUs. When migrating timers of x86 HVM guests between its vCPUs, the locking model used allows for a second vCPU of the same guest (also operating on the timers) to release a lock that it didn't acquire. The most likely effect of the issue is a hang or crash of the hypervisor, i.e., a Denial of Service (DoS). All versions of Xen are affected. Only x86 systems are vulnerable. Arm systems are not vulnerable. Only x86 HVM guests can leverage the vulnerability. x86 PV and PVH cannot leverage the vulnerability. Only guests with more than one vCPU can exploit the vulnerability.

Notes

AuthorNote
mdeslaur
hypervisor packages are in universe. For
issues in the hypervisor, add appropriate
tags to each section, ex:
Tags_xen: universe-binary

Priority

Medium

Cvss 3 Severity Score

4.7

Score breakdown

Status

Package Release Status
xen
Launchpad, Ubuntu, Debian
bionic Needed

focal
Released (4.11.3+24-g14b62ab3e5-1ubuntu2.3)
groovy Ignored
(end of life)
hirsute Ignored
(end of life)
impish Ignored
(end of life)
jammy Not vulnerable
(4.11.4+37-g3263f257ca-1)
kinetic Not vulnerable
(4.11.4+37-g3263f257ca-1)
lunar Not vulnerable
(4.11.4+37-g3263f257ca-1)
mantic Not vulnerable
(4.11.4+37-g3263f257ca-1)
noble Not vulnerable
(4.11.4+37-g3263f257ca-1)
trusty Does not exist

upstream Needs triage

xenial Needed

Binaries built from this source package are in Universe and so are supported by the community.

Severity score breakdown

Parameter Value
Base score 4.7
Attack vector Local
Attack complexity High
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact None
Availability impact High
Vector CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H