CVE-2021-24041
📋 TL;DR
A missing bounds check in WhatsApp's image blurring code allows an attacker to trigger an out-of-bounds write by sending a malicious image. This could lead to remote code execution or application crashes. Affects WhatsApp and WhatsApp Business for Android users running vulnerable versions.
💻 Affected Systems
- WhatsApp for Android
- WhatsApp Business for Android
📦 What is this software?
Whatsapp by Whatsapp
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution on the victim's device, potentially allowing full device compromise, data theft, or installation of persistent malware.
Likely Case
Application crash leading to denial of service, or limited memory corruption that could be leveraged for further exploitation.
If Mitigated
No impact if patched version is installed, as the vulnerability is fixed in the code.
🎯 Exploit Status
Exploitation requires the attacker to send a malicious image that the victim must receive and process. No public exploit code is known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v2.21.22.7 and later
Vendor Advisory: https://www.whatsapp.com/security/advisories/2021/
Restart Required: Yes
Instructions:
1. Open Google Play Store. 2. Search for WhatsApp or WhatsApp Business. 3. Tap Update if available. 4. Restart the app after update completes.
🔧 Temporary Workarounds
Disable automatic media download
androidPrevent automatic downloading of images which could trigger the vulnerability
Open WhatsApp Settings > Storage and Data > Media Auto-Download > Disable all options
🧯 If You Can't Patch
- Uninstall vulnerable WhatsApp versions and use alternative secure messaging platforms
- Disable WhatsApp notifications and avoid opening images from unknown contacts
🔍 How to Verify
Check if Vulnerable:
Check WhatsApp version in Settings > Help > App Info. If version is below 2.21.22.7, you are vulnerable.Check Version:
Not applicable - check version through app settingsVerify Fix Applied:
Confirm WhatsApp version is 2.21.22.7 or higher in Settings > Help > App Info.📡 Detection & Monitoring
Log Indicators:
- Application crashes with memory corruption errors
- Unusual image processing failures
Network Indicators:
- Large or malformed image files being sent/received
- Unusual image metadata patterns
SIEM Query:
Not applicable - this is client-side vulnerability on mobile devices