CVE-2021-27947
📋 TL;DR
This SQL injection vulnerability in MyBB allows attackers to execute arbitrary SQL commands through the Copy Forum feature in Forum Management. It affects MyBB installations before version 1.8.26 where administrative access is available. Successful exploitation could lead to data theft, modification, or deletion.
💻 Affected Systems
- MyBB
📦 What is this software?
Mybb by Mybb
⚠️ Risk & Real-World Impact
Worst Case
Complete database compromise including user credential theft, privilege escalation, and potential remote code execution through database functions.
Likely Case
Data exfiltration of sensitive forum information, user data theft, and potential administrative account takeover.
If Mitigated
Limited impact with proper input validation and parameterized queries preventing SQL injection.
🎯 Exploit Status
Exploitation requires administrative privileges but SQL injection payloads are well-documented and easy to craft.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.8.26
Vendor Advisory: https://github.com/mybb/mybb/security/advisories/GHSA-jjx8-8mcp-7h65
Restart Required: No
Instructions:
1. Backup your database and files. 2. Download MyBB 1.8.26 or later. 3. Replace affected files with patched versions. 4. Verify functionality.
🔧 Temporary Workarounds
Disable Copy Forum Feature
allTemporarily disable the Copy Forum functionality in Forum Management to prevent exploitation.
Modify admin permissions to remove 'Can Copy Forums' privilege
Input Validation Enhancement
allImplement additional input validation for forum management parameters.
Add parameter validation in admin/modules/forum/management.php
🧯 If You Can't Patch
- Restrict administrative access to trusted IP addresses only
- Implement web application firewall with SQL injection rules
🔍 How to Verify
Check if Vulnerable:
Check MyBB version in Admin CP > Home > Version & Update or examine inc/version.php file.Check Version:
grep "'version'" inc/version.phpVerify Fix Applied:
Verify version is 1.8.26 or later and test Copy Forum functionality with safe inputs.📡 Detection & Monitoring
Log Indicators:
- Unusual SQL queries in database logs
- Multiple failed login attempts to admin panel
- Unexpected forum copy operations
Network Indicators:
- SQL injection patterns in HTTP POST requests to admin/modules/forum/management.php
SIEM Query:
source="web_logs" AND uri="/admin/modules/forum/management.php" AND (method="POST") AND (payload CONTAINS "UNION" OR payload CONTAINS "SELECT" OR payload CONTAINS "INSERT")