CVE-2026-27475
📋 TL;DR
SPIP versions before 4.4.9 contain an insecure deserialization vulnerability in the public area through the table_valeur filter and DATA iterator. Attackers who can inject malicious serialized data (requiring prior access or another vulnerability) can trigger arbitrary object instantiation and potentially achieve remote code execution. This affects all SPIP installations using vulnerable versions with the affected components enabled.
💻 Affected Systems
- SPIP
📦 What is this software?
Spip by Spip
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, and lateral movement within the network.
Likely Case
Privilege escalation from limited access to full administrative control of the SPIP application, potentially leading to website defacement or data manipulation.
If Mitigated
Limited impact if proper input validation and access controls prevent malicious serialized data injection.
🎯 Exploit Status
Exploitation requires the attacker to first inject malicious serialized data through another vulnerability or existing access, then trigger deserialization through the vulnerable components.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.4.9
Vendor Advisory: https://blog.spip.net/Mise-a-jour-de-securite-sortie-de-SPIP-4-4-9.html
Restart Required: Yes
Instructions:
1. Backup your SPIP installation and database. 2. Download SPIP 4.4.9 from the official repository. 3. Replace all files with the new version. 4. Run the update script if prompted. 5. Clear caches and verify functionality.
🔧 Temporary Workarounds
Disable vulnerable filters
allRemove or disable the table_valeur filter and DATA iterator functionality if not required.
Modify SPIP configuration to remove filter references
Comment out or delete filter registration in plugins
🧯 If You Can't Patch
- Implement strict input validation to reject serialized data in user inputs
- Deploy web application firewall rules to detect and block serialized data patterns
🔍 How to Verify
Check if Vulnerable:
Check SPIP version in administration panel or via version.php fileCheck Version:
Check SPIP admin panel or examine ecrire/inc_version.phpVerify Fix Applied:
Confirm version is 4.4.9 or later and test that serialized data inputs are properly sanitized📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests containing serialized data patterns
- Errors related to deserialization or object instantiation
Network Indicators:
- HTTP requests with serialized PHP object patterns in parameters
SIEM Query:
web_requests WHERE uri CONTAINS 'table_valeur' OR params CONTAINS 'O:' AND params CONTAINS 's:'