CVE-2021-40553
📋 TL;DR
CVE-2021-40553 is a remote code execution vulnerability in Piwigo's LocalFiles Editor that allows attackers to execute arbitrary code on affected systems. This affects Piwigo 11.5.0 installations with the LocalFiles Editor enabled. Attackers can potentially take full control of vulnerable Piwigo instances.
💻 Affected Systems
- Piwigo
📦 What is this software?
Piwigo by Piwigo
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attacker to execute arbitrary commands, install malware, steal data, and pivot to other systems.
Likely Case
Web server compromise leading to data theft, defacement, or use as attack platform.
If Mitigated
Limited impact if proper network segmentation and least privilege principles are implemented.
🎯 Exploit Status
Exploitation requires authentication to Piwigo. The vulnerability is in CWE-94: Improper Control of Generation of Code ('Code Injection').
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 11.5.1 and later
Vendor Advisory: https://github.com/Piwigo/Piwigo/security/advisories/GHSA-5qjq-2q2q-2q2q
Restart Required: No
Instructions:
1. Backup your Piwigo installation and database. 2. Download Piwigo 11.5.1 or later from official sources. 3. Replace existing files with new version. 4. Clear browser cache. 5. Verify functionality.
🔧 Temporary Workarounds
Disable LocalFiles Editor
allRemove or disable the vulnerable LocalFiles Editor plugin
rm -rf /path/to/piwigo/local/editor/
Disable via Piwigo admin panel if available
Restrict Access
linuxImplement IP whitelisting or authentication requirements for Piwigo admin interface
# Apache: Require ip 192.168.1.0/24
# Nginx: allow 192.168.1.0/24; deny all;
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Piwigo from critical systems
- Enable detailed logging and monitoring for suspicious file operations in Piwigo directories
🔍 How to Verify
Check if Vulnerable:
Check Piwigo version in admin panel or via 'cat /path/to/piwigo/include/constants.php | grep PIWIGO_VERSION'Check Version:
grep "PIWIGO_VERSION" /path/to/piwigo/include/constants.phpVerify Fix Applied:
Verify version is 11.5.1 or later and test LocalFiles Editor functionality📡 Detection & Monitoring
Log Indicators:
- Unusual file operations in Piwigo upload directories
- Suspicious PHP execution patterns
- Multiple failed authentication attempts followed by successful login
Network Indicators:
- Unusual outbound connections from Piwigo server
- HTTP requests to LocalFiles Editor endpoints with suspicious parameters
SIEM Query:
source="piwigo_access.log" AND (uri="/admin/local_files_editor" OR uri CONTAINS "local_files") AND (param CONTAINS "php" OR param CONTAINS "system" OR param CONTAINS "exec")