Vm VirtualboxApplication · Oracle

CVE-2021-35540

MEDIUM · 5.5 CVSS v3.1 Published 2021-10-20

Fix available

A fix is available. Upgrade to 6.1.28 or later.

See remediation →

57/100

Remediation priority · Elevated

Zero-click

Official description

NVD · unedited

Vulnerability in the Oracle VM VirtualBox product of Oracle Virtualization (component: Core). The supported version that is affected is Prior to 6.1.28. Easily exploitable vulnerability allows low privileged attacker with logon to the infrastructure where Oracle VM VirtualBox executes to compromise Oracle VM VirtualBox. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of Oracle VM VirtualBox. CVSS 3.1 Base Score 5.5 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

Technical summary

dbcve analysis · high confidence

Local denial-of-service vulnerability in Oracle VM VirtualBox Core component. A low-privileged attacker with logon access to the infrastructure can cause VirtualBox to hang or crash repeatedly, resulting in complete denial of service.

MitigationUpgrade Oracle VM VirtualBox to version 6.1.28 or later to resolve this vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions

NVD · CPE data

Vm VirtualboxApplication

Affected:< 6.1.28

CVSS breakdown

From the vector

Attack vector: Local
Complexity: Low
Privileges: Low
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

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

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Check if VirtualBox is installed

Run 'VBoxManage --version' on the command line (Windows, Linux, or macOS). If VBoxManage is not in PATH, navigate to the VirtualBox installation directory (commonly C:\Program Files\Oracle\VirtualBox on Windows or /usr/bin/VBoxManage on Linux) and run it there.

Affected if The command returns a version number, indicating VirtualBox is installed.
Identify the installed version number

Note the full version number returned by the VBoxManage --version command. It will be in the format such as '6.1.26' or '6.1.27'.

Affected if A version number is displayed.
Compare against the vulnerable version range

Compare your installed version to 6.1.28. Check if your version number is lower than 6.1.28 (for example, 6.1.26, 6.1.27, 6.1.0, 6.0.x, etc.).

Affected if Your installed version is less than 6.1.28 (for example, 6.1.27, 6.1.26, or any 6.0.x or 5.x version).

You are affected if VirtualBox is installed and the version is below 6.1.28.

Generated from the published advisory. Verify against your own configuration.

Remediation

dbcve · scoped

Upgrade available Upgrade to 6.1.28 or later

Fixed in 6.1.28

Interim mitigation

Upgrade Oracle VM VirtualBox to version 6.1.28 or later to resolve this vulnerability.

Recommended fix High confidence

6.1.28

Ensure all virtual machines are powered off and backed up if needed
Uninstall the current version of Oracle VM VirtualBox
Download VirtualBox version 6.1.28 or later from the official Oracle VirtualBox website (https://www.virtualbox.org/wiki/Downloads)
Install the new VirtualBox version following the installation wizard prompts
Restart the host system after installation
Verify the installed version is 6.1.28 or later by checking VirtualBox > Help > About VirtualBox

Caveat VirtualBox minor version upgrades typically preserve VM configurations, but always ensure VM backups exist before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Vm Virtualbox Scoped from the published advisory

Consultation2.0 h
Implementation2.0 h
Testing3.0 h
Review / QA1.0 h

8.0 hours of engineering $1,390

Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,224.

Scan for this in your stack

Free · runs locally

dbcve dependency scanner

Check whether your project pulls in CVE-2021-35540 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References

Primary sources

www.oracle.comVendor Advisory
security.gentoo.orgThird Party Advisory
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-35540 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2021-35540?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

A fix existsUpgrade to 6.1.28 or later

Severity 5.5 Medium

Exploit likelihood EPSS, next 30 days 0.4%

Affects: Vm Virtualbox

Remediation

Need this fixed?

Fix this in Vm Virtualbox 8 hrs · Low

Typical engagement from $1,390

Get a fix See the full breakdown ↓

We specialise in CVE remediation. Send your environment and we’ll scope CVE-2021-35540 and return a fixed quote.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

Check your environment

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References