CVE-2021-43266
📋 TL;DR
This vulnerability allows remote code execution in Mahara e-portfolio systems through shell command injection. Attackers can execute arbitrary commands on the server by crafting malicious collection names containing shell metacharacters during PDF export. All Mahara installations running vulnerable versions are affected.
💻 Affected Systems
- Mahara
📦 What is this software?
Mahara by Mahara
Mahara by Mahara
Mahara by Mahara
Mahara by Mahara
Mahara by Mahara
Mahara by Mahara
⚠️ Risk & Real-World Impact
Worst Case
Full server compromise allowing attacker to execute arbitrary commands with web server privileges, potentially leading to data theft, system takeover, or lateral movement.
Likely Case
Remote code execution leading to data exfiltration, installation of backdoors, or disruption of Mahara services.
If Mitigated
Limited impact if proper input validation and shell escaping are implemented, though PDF export functionality may be disrupted.
🎯 Exploit Status
Exploitation requires authenticated user access to create collections with malicious names and trigger PDF export
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 20.04.5, 20.10.4, 21.04.3, 21.10.1 or later
Vendor Advisory: https://mahara.org/interaction/forum/topic.php?id=8952
Restart Required: No
Instructions:
1. Backup your Mahara installation and database. 2. Download the appropriate patched version from mahara.org. 3. Replace vulnerable files with patched versions. 4. Clear caches if applicable.
🔧 Temporary Workarounds
Disable PDF Export
allTemporarily disable PDF export functionality to prevent exploitation
Restrict Collection Creation
allLimit collection creation to trusted administrators only
🧯 If You Can't Patch
- Implement strict input validation to reject collection names containing shell metacharacters
- Apply web application firewall rules to block requests containing shell metacharacters in collection names
🔍 How to Verify
Check if Vulnerable:
Check Mahara version via admin panel or by examining version.php fileCheck Version:
grep -r "\$version" /path/to/mahara/htdocs/version.phpVerify Fix Applied:
Verify installed version is 20.04.5+, 20.10.4+, 21.04.3+, or 21.10.1+📡 Detection & Monitoring
Log Indicators:
- Unusual PDF export requests
- Collection names containing shell metacharacters
- Unexpected shell command execution in system logs
Network Indicators:
- HTTP POST requests to export endpoints with unusual parameters
SIEM Query:
source="mahara_logs" AND ("pdf export" OR "collection export") AND ("|" OR ";" OR "&" OR "$" OR "`")🔗 References
- https://bugs.launchpad.net/mahara/+bug/1942903
- https://bugs.launchpad.net/mahara/+bug/1949527
- https://mahara.org/interaction/forum/topic.php?id=8952
- https://mahara.org/interaction/forum/topic.php?id=8995
- https://bugs.launchpad.net/mahara/+bug/1942903
- https://bugs.launchpad.net/mahara/+bug/1949527
- https://mahara.org/interaction/forum/topic.php?id=8952
- https://mahara.org/interaction/forum/topic.php?id=8995
