WhatsappApplication

CVE-2021-24042

CRITICAL · 9.8 CVSS v3.1 Published 2022-01-04

Fix available

A fix is available. Upgrade to 2.21.23 / 2.21.230 or later.

See remediation →

100/100

Remediation priority · Urgent

Remotely reachable No privileges Zero-click

Official description

NVD · unedited

The calling logic for WhatsApp for Android prior to v2.21.23, WhatsApp Business for Android prior to v2.21.23, WhatsApp for iOS prior to v2.21.230, WhatsApp Business for iOS prior to v2.21.230, WhatsApp for KaiOS prior to v2.2143, WhatsApp Desktop prior to v2.2146 could have allowed an out-of-bounds write if a user makes a 1:1 call to a malicious actor.

Technical summary

dbcve analysis · high confidence

An out-of-bounds write vulnerability exists in the calling logic of WhatsApp for Android, iOS, KaiOS, and Desktop. The flaw can be triggered when a user initiates a 1:1 call with a malicious actor, potentially allowing remote code execution on the victim's device.

MitigationUpdate WhatsApp, WhatsApp Business, WhatsApp Desktop, and WhatsApp for KaiOS to the specified patched versions (v2.21.23 or later for Android, v2.21.230 or later for iOS, v2.2143 or later for KaiOS, v2.2146 or later for Desktop).

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

WhatsappApplication

Affected:< 2.21.23< 2.21.230< 2.2143< 2.2146

CVSS breakdown

From the vector

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

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

Am I affected?

dbcve checks

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

Check WhatsApp version on Android

Open WhatsApp, tap Settings > Help > About WhatsApp. Note the version number shown under 'Version'. Compare it against 2.21.23 - if it is lower (for example, 2.21.22), the installation is vulnerable.

Affected if The installed version is below 2.21.23 on Android devices using WhatsApp.
Check WhatsApp version on iOS

Open WhatsApp, go to Settings > Help > About WhatsApp. Note the version number under 'Version'. Compare it against 2.21.230 - if it is lower, the installation is vulnerable.

Affected if The installed version is below 2.21.230 on iOS devices using WhatsApp.
Check WhatsApp version on Desktop

Open WhatsApp Desktop, click the three-dot menu > Help > About WhatsApp. Note the version displayed. Compare it against 2.2146 - if lower, the installation is vulnerable.

Affected if The installed version is below 2.2146 on Desktop installations of WhatsApp.
Check WhatsApp version on KaiOS

Open WhatsApp on KaiOS device, navigate to Settings > About > Software. Note the version number shown. Compare it against 2.2143 - if it is lower, the installation is vulnerable.

Affected if The installed version is below 2.2143 on KaiOS devices using WhatsApp.
Verify if calling feature is in use

This vulnerability is triggered specifically during 1:1 voice or video calls. Check whether you or users in your organization use WhatsApp's call functionality. The flaw requires the calling feature to be actively used or available on the device.

Affected if Users initiate or receive 1:1 voice or video calls through WhatsApp on affected versions.

A user is affected if their installed WhatsApp version is below the platform-specific threshold (2.21.23 Android, 2.21.230 iOS, 2.2143 KaiOS, 2.2146 Desktop) AND they use the 1:1 call feature.

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

Remediation

dbcve · scoped

Upgrade available Upgrade to 2.21.23 / 2.21.230 / 2.2143 or later

Fixed in 2.21.232.21.2302.2143

Interim mitigation

Update WhatsApp, WhatsApp Business, WhatsApp Desktop, and WhatsApp for KaiOS to the specified patched versions (v2.21.23 or later for Android, v2.21.230 or later for iOS, v2.2143 or later for KaiOS, v2.2146 or later for Desktop).

Recommended fix High confidence

WhatsApp for Android v2.21.23+, WhatsApp Business for Android v2.21.23+, WhatsApp for iOS v2.21.230+, WhatsApp Business for iOS v2.21.230+, WhatsApp for KaiOS v2.2143+, WhatsApp Desktop v2.2146+

Identify your WhatsApp application (WhatsApp, WhatsApp Business, or WhatsApp Desktop) and operating system (Android, iOS, KaiOS, or Desktop)
Open the respective app store for your platform: Google Play Store for Android, Apple App Store for iOS, or visit the official WhatsApp website for Desktop/KaiOS
Search for WhatsApp or WhatsApp Business in your app store
Verify your current version by checking the app info/settings
If your version is below the fixed release, tap 'Update' or download the latest version from the official source
For Desktop users, download the latest version from https://www.whatsapp.com/download/
After updating, verify the version number matches or exceeds the fixed release for your platform
Restart the application to ensure the update is fully applied

Caveat Standard app update with no expected breaking changes; all users should update immediately due to critical severity

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

Fix this in Whatsapp Scoped from the published advisory

Consultation1.0 h
Testing1.0 h
Review / QA1.0 h

3.0 hours of engineering $750

Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,200.

Scan for this in your stack

Free · runs locally

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References

Primary sources

www.whatsapp.comNot ApplicableVendor Advisory
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-24042 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2021-24042?

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 2.21.23 / 2.21.230 or later

Severity 9.8 Critical

Exploit likelihood EPSS, next 30 days 1.2%

Affects: Whatsapp

Remediation

A high-priority fix

Fix this in Whatsapp 3 hrs · Low

Typical engagement from $750

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2021-24042 and return a fixed quote and timeline.

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