CVE-2025-59535
📋 TL;DR
DNN CMS versions before 10.1.0 allow attackers to load arbitrary themes via query parameters, potentially exposing vulnerabilities in unused themes. This affects all DNN installations with vulnerable themes, even if those themes aren't actively deployed. Site owners may be unaware their sites are vulnerable to theme-specific exploits.
💻 Affected Systems
- DNN Platform (formerly DotNetNuke)
📦 What is this software?
Dotnetnuke by Dnnsoftware
⚠️ Risk & Real-World Impact
Worst Case
Attackers could load themes containing remote code execution vulnerabilities, gaining full control of the web server and potentially pivoting to internal networks.
Likely Case
Attackers exploit known vulnerabilities in unused themes to perform cross-site scripting, data theft, or limited server-side code execution.
If Mitigated
With proper input validation and theme whitelisting, attackers cannot load arbitrary themes, limiting exposure to only actively used themes.
🎯 Exploit Status
Exploitation requires knowledge of installed themes and their specific vulnerabilities.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 10.1.0
Vendor Advisory: https://github.com/dnnsoftware/Dnn.Platform/security/advisories/GHSA-wq2j-w9pm-7x2p
Restart Required: No
Instructions:
1. Backup your DNN installation and database. 2. Download DNN Platform 10.1.0 or later. 3. Follow the official upgrade guide at https://dnndocs.com/. 4. Test functionality after upgrade.
🔧 Temporary Workarounds
Remove unused themes
allDelete all themes that are not actively used on any pages to eliminate potential attack surface.
Navigate to Host > Extensions > Themes, select unused themes, click Delete
Implement input validation
allAdd custom validation to reject theme parameters not matching allowed themes.
Modify web.config or create custom HTTP module to validate theme parameters
🧯 If You Can't Patch
- Audit and remove all unused themes from the installation
- Implement WAF rules to block requests containing theme parameters
🔍 How to Verify
Check if Vulnerable:
Check DNN version in Host > Site Settings > Basic Settings. If version is below 10.1.0, you are vulnerable.Check Version:
Check Host > Site Settings > Basic Settings in DNN admin panelVerify Fix Applied:
After upgrading, verify version is 10.1.0 or higher and test that theme parameters are properly validated.📡 Detection & Monitoring
Log Indicators:
- HTTP requests with unusual theme parameters in query strings
- Errors from theme loading failures
Network Indicators:
- Unusual theme parameter values in HTTP GET requests
SIEM Query:
web.url:*theme=* AND NOT web.url:*theme=standard