CVE-2026-24833: DNN (DotNetNuke) XSS Vulnerability

CVE-2026-24833 Overview

CVE-2026-24833 is a Cross-Site Scripting (XSS) vulnerability affecting DNN (formerly DotNetNuke), an open-source web content management platform (CMS) in the Microsoft ecosystem. The vulnerability exists in versions prior to 9.13.10 and 10.2.0, where a module could be installed with richtext in its description field containing malicious scripts that execute for users accessing the Persona Bar administrative interface.

Critical Impact

Attackers with high privileges can inject persistent malicious scripts through module descriptions, potentially compromising administrative users and enabling session hijacking, credential theft, or further system compromise within the CMS environment.

Affected Products

• DNN Platform versions prior to 9.13.10
• DNN Platform versions prior to 10.2.0
• DNN installations utilizing the Persona Bar administrative interface

Discovery Timeline

• 2026-01-28 - CVE CVE-2026-24833 published to NVD
• 2026-01-29 - Last updated in NVD database

Technical Details for CVE-2026-24833

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The flaw resides in the module installation process where the description field accepts richtext content without proper sanitization. When an administrative user views module information in the Persona Bar, any embedded JavaScript within the description field executes in the context of their browser session.

The attack requires network access and elevated privileges to install modules, combined with user interaction from an administrator viewing the malicious module description. However, once the payload is in place, it persists within the CMS and can affect any user who accesses the compromised module's details through the administrative interface. The changed scope indicates that this vulnerability can impact resources beyond the vulnerable component itself.

Root Cause

The root cause lies in insufficient input validation and output encoding within the DNN module installation workflow. The platform fails to properly sanitize richtext content in module description fields before storing it in the database and rendering it to administrators in the Persona Bar. This allows HTML and JavaScript code to be preserved and later executed when the description content is displayed.

Attack Vector

The attack vector for this vulnerability follows a stored XSS pattern:

1. An attacker with module installation privileges creates or modifies a module package containing malicious JavaScript embedded within the description field
2. The module is installed on the target DNN platform, persisting the malicious payload in the database
3. When an administrator accesses the Persona Bar and views the module's description, the malicious script executes within their browser
4. The attacker can leverage the executed script to steal session cookies, perform actions as the administrator, or inject additional payloads

The vulnerability requires high privileges to exploit initially (ability to install modules), but the impact extends to other administrative users who interact with the compromised module description.

Detection Methods for CVE-2026-24833

Indicators of Compromise

• Unusual JavaScript patterns within module description fields in the DNN database
• Unexpected network requests originating from administrative Persona Bar sessions to external domains
• Modified or suspicious module packages installed on the platform with richtext descriptions containing script tags or event handlers
• Administrative session anomalies such as unexpected privilege escalation or configuration changes

Detection Strategies

• Implement Content Security Policy (CSP) headers to detect and block inline script execution attempts
• Monitor DNN database tables for module descriptions containing suspicious HTML tags like <script>, <iframe>, or event handlers such as onerror, onload
• Deploy web application firewalls (WAF) to detect XSS payloads in module installation requests
• Conduct regular audits of installed modules and their associated metadata for anomalous content

Monitoring Recommendations

• Enable detailed logging for module installation and modification events within DNN
• Configure alerts for administrative actions involving module management in the Persona Bar
• Monitor browser-side console errors and network requests during administrative sessions for signs of script injection
• Implement integrity monitoring for module packages and their metadata

How to Mitigate CVE-2026-24833

Immediate Actions Required

• Upgrade DNN Platform to version 9.13.10 or 10.2.0 immediately to remediate the vulnerability
• Audit all currently installed modules for suspicious content in description fields
• Review recent module installations and verify their legitimacy and source
• Restrict module installation privileges to trusted administrators only

Patch Information

DNN Software has addressed this vulnerability in versions 9.13.10 and 10.2.0. The fix implements proper sanitization and encoding of richtext content in module description fields to prevent script execution. Organizations should prioritize upgrading to these patched versions. For detailed information about the security fix, refer to the GitHub Security Advisory.

Workarounds

• Implement strict access controls limiting who can install or modify modules on the platform
• Deploy a Web Application Firewall (WAF) to filter potentially malicious content in module installation requests
• Configure Content Security Policy headers to prevent inline script execution as an additional defense layer
• Manually sanitize existing module descriptions by removing any HTML or JavaScript content until the patch can be applied

# Review web.config to add Content Security Policy headers as a temporary mitigation
# Add the following to your DNN web.config in the <system.webServer><httpProtocol><customHeaders> section:
# <add name="Content-Security-Policy" value="script-src 'self'; object-src 'none';" />