CVE-2026-25615
📋 TL;DR
This vulnerability in Blesta billing software allows attackers to perform object injection attacks by sending specially crafted data. This affects all Blesta installations running versions 3.x through 5.x before 5.13.3, potentially allowing remote code execution or other malicious actions.
💻 Affected Systems
- Blesta
📦 What is this software?
Blesta by Phillipsdata
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, and lateral movement within the network.
Likely Case
Arbitrary code execution with the privileges of the web server process, potentially allowing data manipulation, privilege escalation, or installation of backdoors.
If Mitigated
Limited impact if proper input validation and sanitization are implemented at the application layer, though the core vulnerability remains.
🎯 Exploit Status
Object injection vulnerabilities typically require some understanding of the application's object structure but can be exploited without authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.13.3
Vendor Advisory: https://www.blesta.com/2026/01/28/security-advisory/
Restart Required: No
Instructions:
1. Backup your Blesta installation and database. 2. Download Blesta 5.13.3 or later from the official website. 3. Follow the standard Blesta upgrade procedure. 4. Verify the upgrade completed successfully.
🔧 Temporary Workarounds
Input Validation Filter
allImplement strict input validation and sanitization for all user-supplied data before deserialization.
🧯 If You Can't Patch
- Implement web application firewall (WAF) rules to block suspicious serialized object patterns
- Restrict network access to Blesta administration interfaces to trusted IP addresses only
🔍 How to Verify
Check if Vulnerable:
Check your Blesta version in the admin panel under Settings > System > General. If version is between 3.0 and 5.13.2 inclusive, you are vulnerable.Check Version:
Check Blesta admin panel or examine the /config/blesta.php file for version informationVerify Fix Applied:
After upgrading, verify the version shows 5.13.3 or higher in the admin panel.📡 Detection & Monitoring
Log Indicators:
- Unusual PHP object serialization patterns in request logs
- Errors related to unserialize() function
- Suspicious POST requests with serialized data
Network Indicators:
- HTTP requests containing serialized PHP objects (O: patterns)
- Requests to Blesta endpoints with unusual payloads
SIEM Query:
source="*blesta*" AND ("unserialize" OR "O:" OR "C:" OR "a:" in request_body)