---
title: "CVE-2021-28693\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2021-28693?format=md
keywords: index, follow
---

# CVE-2021-28693

Publication date 30 June 2021

Last updated 11 July 2025

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**5.5 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2021-28693?format=md#impact-score)

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## Description

xen/arm: Boot modules are not scrubbed The bootloader will load boot
modules (e.g. kernel, initramfs...) in a temporary area before they are
copied by Xen to each domain memory. To ensure sensitive data is not leaked
from the modules, Xen must "scrub" them before handing the page over to the
allocator. Unfortunately, it was discovered that modules will not be
scrubbed on Arm.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2021-28693?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| xen | 26.04 LTS resolute | Needs evaluation |
| 25.10 questing | Ignored end of life, was needs-triage |
| 25.04 plucky | Ignored end of life, was needs-triage |
| 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 |
| 20.10 groovy | 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 |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)

## Notes

---

### [mdeslaur](https://launchpad.net/~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

CVSS version:
CVSS v3.0

**Base score**

5.5 · Medium

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Local |
  | Attack complexity | Low |
  | Privileges required | Low |
  | User interaction | None |
  | Scope | Unchanged |
  | Confidentiality impact | High |
  | Integrity impact | None |
  | Availability impact | None |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 5.5 · Medium |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-28693)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2021-28693)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2021-28693)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2021-28693)

### Other references

* <https://xenbits.xen.org/xsa/advisory-372.html>
* <https://www.cve.org/CVERecord?id=CVE-2021-28693>