CVE-2021-28698

Description

long running loops in grant table handling In order to properly monitor resource use, Xen maintains information on the grant mappings a domain may create to map grants offered by other domains. In the process of carrying out certain actions, Xen would iterate over all such entries, including ones which aren't in use anymore and some which may have been created but never used. If the number of entries for a given domain is large enough, this iterating of the entire table may tie up a CPU for too long, starving other domains or causing issues in the hypervisor itself. Note that a domain may map its own grants, i.e. there is no need for multiple domains to be involved here. A pair of "cooperating" guests may, however, cause the effects to be more severe.

How to fix CVE-2021-28698

To remediate CVE-2021-28698, upgrade the affected package to a fixed version below.

• —upgrade to 4.13.3-r2 or later
• —upgrade to 4.14.3-1~deb11u1 or later

Is CVE-2021-28698 being exploited?

Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.

Affected packages (2)

• from 0, < 4.13.3-r2
• from 0, < 4.14.3-1~deb11u1

CVSS scores

References (2)

• ADVISORYsecurity.alpinelinux.org/vuln/CVE-2021-28698
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2021-28698