CVE-2025-67851
📋 TL;DR
A formula injection vulnerability in Moodle allows remote attackers to embed malicious formulas in exported data. When users export this data and open it in spreadsheet applications like Excel or LibreOffice, arbitrary formulas can execute, potentially compromising data integrity. This affects all Moodle instances with data export functionality enabled.
💻 Affected Systems
- Moodle
📦 What is this software?
Moodle by Moodle
Moodle by Moodle
Moodle by Moodle
Moodle by Moodle
Moodle by Moodle
⚠️ Risk & Real-World Impact
Worst Case
Attackers could execute arbitrary formulas in spreadsheets, potentially leading to data corruption, information disclosure via external calls, or execution of malicious macros if combined with other vulnerabilities.
Likely Case
Data integrity issues in exported spreadsheets, potential for phishing attacks via formula execution, and spreadsheet corruption affecting business operations.
If Mitigated
Limited to spreadsheet-level impact without affecting the Moodle server itself; proper input validation prevents exploitation.
🎯 Exploit Status
Exploitation requires attacker to have ability to input data that gets exported, and victim to open exported spreadsheet in vulnerable spreadsheet application
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Moodle security advisories for specific patched versions
Vendor Advisory: https://moodle.org/mod/forum/discuss.php?d=471301
Restart Required: No
Instructions:
1. Check Moodle security advisory for patched version. 2. Backup your Moodle installation. 3. Update to the patched version using Moodle's update mechanism. 4. Verify export functionality works correctly.
🔧 Temporary Workarounds
Disable data export functionality
allTemporarily disable data export features in Moodle until patched
Navigate to Site administration > Advanced features > Enable data export (uncheck)
Implement input validation
allAdd custom validation to sanitize data before export
Implement input filtering in custom code to escape formula characters (=, +, -, @) before export
🧯 If You Can't Patch
- Educate users to never open exported spreadsheets from untrusted sources
- Configure spreadsheet applications to disable automatic formula execution
🔍 How to Verify
Check if Vulnerable:
Check if your Moodle version is within affected range by comparing with Moodle security advisoryCheck Version:
Navigate to Site administration > Notifications in Moodle admin panel to see current versionVerify Fix Applied:
Test data export functionality with formula characters and verify they are properly escaped in output📡 Detection & Monitoring
Log Indicators:
- Unusual export activity patterns
- Multiple failed export attempts
Network Indicators:
- Large data export requests containing formula characters
SIEM Query:
source="moodle_logs" AND (event="data_export" AND data CONTAINS "=")