CVE-2021-28706

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

2.2% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-11-24 01:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:46 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 2.2% in the next 30 days (EPSS).
• Severity: 8.6 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-11-24 01:15 UTC

Last modified

2026-06-17 03:46 UTC

Exploit probability

2.2% · EPSS, next 30 days

Weakness

CWE-770 · Allocation without limits

Record status

Modified

Affected

• Xen < 4.12
• Fedoraproject Fedora 34
• Fedoraproject Fedora 35
• Debian Linux 11.0

Attack profile CVSS 3.1 · 8.6

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Changed

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-28706.md and follow it. Check whether this project is affected by CVE-2021-28706. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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