CVE-2021-40826
📋 TL;DR
CVE-2021-40826 is a memory corruption vulnerability in Clementine Music Player's MP3 parsing functionality that allows attackers to crash the application or execute arbitrary code. Users who open malicious MP3 files or load crafted remote streams are affected. The vulnerability requires user interaction but can lead to full system compromise under the current user's privileges.
💻 Affected Systems
- Clementine Music Player
📦 What is this software?
Clementine by Clementine Player
⚠️ Risk & Real-World Impact
Worst Case
Arbitrary code execution with the privileges of the logged-in Windows user, potentially leading to full system compromise, data theft, or ransomware deployment.
Likely Case
Application crash (Denial of Service) when opening malicious MP3 files, disrupting music playback functionality.
If Mitigated
Limited impact if application runs with minimal privileges and network access is restricted.
🎯 Exploit Status
Exploitation requires user interaction to open a malicious file. The vulnerability is in user-space memory handling, making exploitation relatively straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.4.0 and later
Vendor Advisory: https://github.com/clementine-player/Clementine/releases
Restart Required: Yes
Instructions:
1. Download Clementine 1.4.0 or later from the official GitHub releases page. 2. Uninstall the old version. 3. Install the new version. 4. Restart the application.
🔧 Temporary Workarounds
Disable MP3 file association
allPrevent Clementine from automatically opening MP3 files by changing the default file association to another media player.
Windows: Control Panel > Default Programs > Set Associations
Linux: update-alternatives --config x-www-browser
macOS: Right-click MP3 file > Get Info > Open With > Change All
Network restriction
allBlock Clementine from accessing remote streams via firewall rules.
Windows: netsh advfirewall firewall add rule name="Block Clementine" dir=out program="C:\Program Files\Clementine\clementine.exe" action=block
Linux: sudo ufw deny out from any to any app clementine
macOS: sudo pfctl -t clementine -T add /Applications/Clementine.app/Contents/MacOS/clementine
🧯 If You Can't Patch
- Uninstall Clementine and use an alternative media player that is not affected by this vulnerability.
- Implement application whitelisting to prevent execution of Clementine entirely.
🔍 How to Verify
Check if Vulnerable:
Check Clementine version: Help > About Clementine. If version is 1.3.1 or earlier, you are vulnerable.Check Version:
Windows: clementine.exe --version, Linux: clementine --version, macOS: /Applications/Clementine.app/Contents/MacOS/clementine --versionVerify Fix Applied:
After updating, verify version is 1.4.0 or later in Help > About Clementine.📡 Detection & Monitoring
Log Indicators:
- Application crash logs mentioning clementine.exe with access violation at address 0x3aa207
- Windows Event Logs: Application Error with Fault Module Name: clementine.exe
Network Indicators:
- Unusual outbound connections from Clementine to unknown IP addresses hosting MP3 files
SIEM Query:
source="windows" AND event_id=1000 AND process_name="clementine.exe" AND fault_offset="0x3aa207"