CVE-2021-47781
📋 TL;DR
CVE-2021-47781 is a critical buffer overflow vulnerability in Cmder Console Emulator version 1.3.18 that allows attackers to cause denial of service by crafting malicious .cmd files. When a user opens a specially crafted .cmd file containing repeated characters, the console emulator's buffer is overwhelmed, crashing the application. This affects all users running the vulnerable version of Cmder.
💻 Affected Systems
- Cmder Console Emulator
⚠️ 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 and denial of service, potentially disrupting workflow and causing data loss if unsaved work is present.
Likely Case
Application crash requiring restart, disrupting user productivity and potentially causing minor data loss.
If Mitigated
No impact if patched version is installed or workarounds are implemented.
🎯 Exploit Status
Exploit code is publicly available on Exploit-DB (ID 50401). Attack requires user interaction to open malicious file.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 1.3.19 and later
Vendor Advisory: https://github.com/cmderdev/cmder
Restart Required: Yes
Instructions:
1. Download latest Cmder version from official GitHub repository. 2. Uninstall vulnerable version. 3. Install updated version. 4. Restart system.
🔧 Temporary Workarounds
Avoid opening untrusted .cmd files
windowsDo not open .cmd files from untrusted sources or unknown senders.
Use alternative terminal
windowsTemporarily use Windows Terminal, PowerShell, or Command Prompt instead of Cmder.
🧯 If You Can't Patch
- Restrict execution of .cmd files via Group Policy or application whitelisting.
- Implement user awareness training about opening suspicious files.
🔍 How to Verify
Check if Vulnerable:
Check Cmder version by opening Cmder and typing 'cmder --version' or checking About in settings.Check Version:
cmder --versionVerify Fix Applied:
Verify version is 1.3.19 or higher using 'cmder --version' command.📡 Detection & Monitoring
Log Indicators:
- Application crash logs from Cmder
- Windows Event Logs showing application failures
Network Indicators:
- Unusual file transfers of .cmd files via email or network shares
SIEM Query:
EventID=1000 OR EventID=1001 Source=Cmder.exe