CVE-2021-25976
📋 TL;DR
This CSRF vulnerability in PiranhaCMS allows attackers to trick authenticated administrators into performing unauthorized actions like deleting users, roles, posts, or media folders by crafting malicious requests. It affects all PiranhaCMS installations from version 4.0.0-alpha1 through 9.2.0 where administrators access the management interface.
💻 Affected Systems
- PiranhaCMS
📦 What is this software?
Piranha Cms by Dotnetfoundation
Piranha Cms by Dotnetfoundation
Piranha Cms by Dotnetfoundation
Piranha Cms by Dotnetfoundation
Piranha Cms by Dotnetfoundation
Piranha Cms by Dotnetfoundation
Piranha Cms by Dotnetfoundation
Piranha Cms by Dotnetfoundation
Piranha Cms by Dotnetfoundation
Piranha Cms by Dotnetfoundation
Piranha Cms by Dotnetfoundation
Piranha Cms by Dotnetfoundation
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of CMS content and user management - attackers could delete all users, posts, and media, effectively destroying the website's content and administrative access.
Likely Case
Targeted content manipulation or deletion - attackers would typically delete specific posts, users, or media items to disrupt operations or deface the website.
If Mitigated
No impact if proper CSRF tokens are implemented and validated on all state-changing requests.
🎯 Exploit Status
Exploitation requires an authenticated administrator to visit a malicious page while logged into PiranhaCMS. Attackers need to know specific object IDs, which can often be guessed or enumerated.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 9.2.1 and later
Vendor Advisory: https://github.com/PiranhaCMS/piranha.core/commit/e42abacdd0dd880ce9cf6607efcc24646ac82eda
Restart Required: No
Instructions:
1. Update PiranhaCMS to version 9.2.1 or later. 2. If using source code, apply the commit e42abacdd0dd880ce9cf6607efcc24646ac82eda. 3. No restart required for typical web applications.
🔧 Temporary Workarounds
Implement CSRF Protection Middleware
allAdd custom middleware to validate anti-CSRF tokens on all POST, PUT, DELETE requests in the management area.
Implement custom middleware that checks for valid __RequestVerificationToken on state-changing endpoints
Restrict Management Interface Access
allLimit access to the PiranhaCMS management interface to specific IP addresses or VPN-only access.
Configure web server (IIS/Apache/Nginx) to restrict /manager path to trusted IPs
🧯 If You Can't Patch
- Implement SameSite=Strict cookies for authentication to prevent CSRF from external sites
- Require re-authentication for destructive actions like deletions
🔍 How to Verify
Check if Vulnerable:
Check if your PiranhaCMS version is between 4.0.0-alpha1 and 9.2.0 inclusive. Review if management endpoints lack CSRF token validation.Check Version:
Check the PiranhaCMS package version in your project file or via the admin interfaceVerify Fix Applied:
Verify version is 9.2.1 or later. Test that management endpoints now require and validate CSRF tokens.📡 Detection & Monitoring
Log Indicators:
- Multiple DELETE/POST requests to management endpoints without referrer headers
- Unusual deletion patterns from single administrator sessions
Network Indicators:
- HTTP requests to management endpoints with missing or invalid CSRF tokens
- Requests originating from unexpected referrers
SIEM Query:
web_access_logs WHERE (path CONTAINS '/manager/' OR path CONTAINS '/admin/') AND (method = 'POST' OR method = 'DELETE') AND (referrer IS NULL OR referrer NOT CONTAINS 'your-domain.com')🔗 References
- https://github.com/PiranhaCMS/piranha.core/commit/e42abacdd0dd880ce9cf6607efcc24646ac82eda
- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25976
- https://github.com/PiranhaCMS/piranha.core/commit/e42abacdd0dd880ce9cf6607efcc24646ac82eda
- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25976
