CVE-2021-28706

Publication date 24 November 2021

Last updated 11 July 2025

Ubuntu priority

Cvss 3 Severity Score

Description

guests may exceed their designated memory limit When a guest is permitted to have close to 16TiB of memory, it may be able to issue hypercalls to increase its memory allocation beyond the administrator established limit. This is a result of a calculation done with 32-bit precision, which may overflow. It would then only be the overflowed (and hence small) number which gets compared against the established upper bound.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
xen	25.10 questing	Needs evaluation
	25.04 plucky	Needs evaluation
	24.10 oracular	Ignored end of life, was needs-triage
	24.04 LTS noble	Needs evaluation
	23.10 mantic	Ignored end of life, was needs-triage
	23.04 lunar	Ignored end of life, was needs-triage
	22.10 kinetic	Ignored end of life, was needs-triage
	22.04 LTS jammy	Needs evaluation
	21.10 impish	Ignored end of life
	21.04 hirsute	Ignored end of life
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation
	14.04 LTS trusty	Not in release

Notes

mdeslaur

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

Severity score breakdown

Parameter	Value
Base score	8.6 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Changed
Confidentiality	None
Integrity impact	None
Availability impact	High
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H