CVE-2026-24784: DNN (DotNetNuke) XSS Vulnerability

CVE-2026-24784 Overview

CVE-2026-24784 is a stored Cross-Site Scripting (XSS) vulnerability affecting DNN (formerly DotNetNuke), an open-source web content management platform (CMS) in the Microsoft ecosystem. Starting in version 9.0.0 and prior to versions 9.13.10 and 10.2.0, a content editor with elevated privileges could inject malicious scripts into module headers or footers that would then execute in the browsers of other users viewing those pages.

Critical Impact

Authenticated content editors can leverage this stored XSS vulnerability to execute arbitrary JavaScript in the context of other users' sessions, potentially leading to session hijacking, credential theft, or administrative account compromise.

Affected Products

• DNN Platform versions 9.0.0 through 9.13.9
• DNN Platform versions 10.0.0 through 10.1.x
• Any DNN-based websites running unpatched versions within the affected range

Discovery Timeline

• 2026-01-28 - CVE CVE-2026-24784 published to NVD
• 2026-01-29 - Last updated in NVD database

Technical Details for CVE-2026-24784

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting (XSS). The flaw exists in how DNN handles content input within module header and footer fields. Users with content editor privileges can inject arbitrary JavaScript code that persists in the database and executes whenever other users, including administrators, view pages containing the affected modules.

The stored nature of this XSS vulnerability makes it particularly dangerous as the malicious payload persists across sessions and can affect multiple victims without requiring further attacker interaction. When an administrator views a page containing the injected script, the malicious code executes with the administrator's session context, potentially allowing the attacker to escalate privileges or perform unauthorized administrative actions.

Root Cause

The root cause of this vulnerability is insufficient input sanitization and output encoding in the module header and footer fields within the DNN platform. The application fails to properly validate and neutralize user-supplied input before storing it in the database and subsequently rendering it in HTML output. Content editors, who are trusted with elevated permissions to manage site content, can abuse this trust boundary by injecting script elements that bypass the expected content restrictions.

Attack Vector

The attack vector is network-based and requires the attacker to have authenticated access with content editor privileges. The attack flow involves:

1. An attacker with content editor privileges accesses the DNN administrative interface
2. The attacker navigates to module configuration settings where header/footer customization is available
3. Malicious JavaScript is injected into the header or footer field of a module
4. The payload is stored in the database without proper sanitization
5. When other users (including administrators) view pages containing the compromised module, the injected script executes in their browser context

The injected scripts can perform actions such as stealing session cookies, redirecting users to phishing pages, modifying page content, or making authenticated API requests on behalf of the victim. Since this affects module headers and footers, the malicious code can potentially execute on every page where the affected module is deployed.

Detection Methods for CVE-2026-24784

Indicators of Compromise

• Unexpected <script> tags or JavaScript event handlers in module header/footer database fields
• Anomalous network requests originating from client browsers to external domains when viewing DNN pages
• Unusual session activity or administrative actions performed without corresponding administrator login events
• Reports from users experiencing unexpected redirects or browser behavior when accessing the CMS

Detection Strategies

• Implement Content Security Policy (CSP) headers with strict script-src directives to detect and block inline script execution
• Deploy Web Application Firewall (WAF) rules to inspect and alert on script injection patterns in form submissions
• Monitor database tables storing module configuration data for entries containing script tags or JavaScript event handlers
• Enable DNN platform audit logging to track changes to module configurations by content editors

Monitoring Recommendations

• Configure SIEM alerts for unusual patterns in web server logs, particularly POST requests to module configuration endpoints
• Implement real-time monitoring of DNN audit logs for bulk or suspicious changes to module settings
• Deploy browser-based telemetry to detect client-side script execution anomalies across the user base
• Regularly scan stored content in the database for known XSS patterns and payloads

How to Mitigate CVE-2026-24784

Immediate Actions Required

• Upgrade DNN Platform to version 9.13.10 or 10.2.0 immediately to apply the security fix
• Review all existing module header and footer configurations for signs of script injection
• Audit content editor accounts and revoke unnecessary privileges pending the upgrade
• Implement Web Application Firewall rules to block script injection attempts as a temporary measure

Patch Information

DNN Software has released patched versions that address this vulnerability. Organizations should upgrade to version 9.13.10 for the 9.x branch or version 10.2.0 for the 10.x branch. The fix implements proper input sanitization and output encoding for module header and footer fields to prevent script injection. Detailed information about the security fix is available in the GitHub Security Advisory.

Workarounds

• Implement strict Content Security Policy (CSP) headers to prevent execution of inline scripts as a defense-in-depth measure
• Temporarily disable or restrict access to module header/footer customization features until the patch can be applied
• Deploy WAF rules that specifically filter script-related HTML tags and JavaScript event handlers in form submissions
• Conduct a security review of all content editor accounts and reduce privileges to the minimum necessary