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CVE-2020-25601

Published: 23 September 2020

An issue was discovered in Xen through 4.14.x. There is a lack of preemption in evtchn_reset() / evtchn_destroy(). In particular, the FIFO event channel model allows guests to have a large number of event channels active at a time. Closing all of these (when resetting all event channels or when cleaning up after the guest) may take extended periods of time. So far, there was no arrangement for preemption at suitable intervals, allowing a CPU to spend an almost unbounded amount of time in the processing of these operations. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. All Xen versions are vulnerable in principle. Whether versions 4.3 and older are vulnerable depends on underlying hardware characteristics.

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 base score: 5.5

Status

Package Release Status
xen
Launchpad, Ubuntu, Debian
bionic Needed

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

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.