CVE-2021-47784
📋 TL;DR
CVE-2021-47784 is a denial of service vulnerability in Cyberfox Web Browser where attackers can crash the application by pasting an excessively large payload (9,000,000 bytes) into the search bar. This affects users of Cyberfox 52.9.1 who could experience application crashes from malicious inputs.
💻 Affected Systems
- Cyberfox Web Browser
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete application crash requiring restart, potentially causing data loss in unsaved sessions or disrupting user workflow.
Likely Case
Application becomes unresponsive and crashes, forcing users to restart the browser and lose any unsaved work.
If Mitigated
Minimal impact if browser is patched or workarounds are implemented to prevent the overflow.
🎯 Exploit Status
Exploit requires user to paste payload into search bar. Proof of concept available on Exploit-DB (ID 50336).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://web.archive.org/web/20180906035057/https://cyberfox.8pecxstudios.com/
Restart Required: No
Instructions:
No official patch available. Consider upgrading to a different browser or implementing workarounds.
🔧 Temporary Workarounds
Disable JavaScript in search bar
allConfigure browser to prevent JavaScript execution in search bar inputs
Input validation extension
allInstall browser extension that validates and limits input size in form fields
🧯 If You Can't Patch
- Switch to alternative web browser with active security updates
- Implement network filtering to block known malicious payloads targeting this vulnerability
🔍 How to Verify
Check if Vulnerable:
Check Cyberfox version in Help > About Cyberfox. If version is 52.9.1, system is vulnerable.Check Version:
Not applicable - check via browser GUI Help > About CyberfoxVerify Fix Applied:
Test by attempting to paste large payload (9MB+) into search bar. If browser crashes, vulnerability exists.📡 Detection & Monitoring
Log Indicators:
- Application crash logs
- Unexpected browser termination events
- Large input size warnings in application logs
Network Indicators:
- Unusual large data transfers to browser process
- Patterns of repeated browser crashes from same source
SIEM Query:
source="browser_logs" AND (event="crash" OR event="termination") AND process="cyberfox.exe"