CVE-2026-24838: DNN (DotNetNuke) XSS Vulnerability

CVE-2026-24838 Overview

CVE-2026-24838 is a stored cross-site scripting (XSS) vulnerability in DNN (formerly DotNetNuke), an open-source web content management platform built on the Microsoft .NET ecosystem. The flaw exists in versions prior to 9.13.10 and 10.2.0. Module titles accept rich text input that can contain script content, which the platform renders without sufficient sanitization in certain scenarios. An authenticated attacker with privileges to set module titles can inject scripts that execute in the browser of any user who views the affected page. The DNN maintainers addressed the issue in versions 9.13.10 and 10.2.0.

Critical Impact

Authenticated attackers can inject JavaScript through module titles to steal session tokens, perform actions on behalf of other users, or redirect victims to attacker-controlled content.

Affected Products

• DNN Platform (DotNetNuke) versions prior to 9.13.10
• DNN Platform (DotNetNuke) versions prior to 10.2.0
• Sites running affected DNN versions with multi-user content editing

Discovery Timeline

• 2026-01-28 - CVE-2026-24838 published to the National Vulnerability Database
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2026-24838

Vulnerability Analysis

The vulnerability is a stored cross-site scripting issue classified as [CWE-79]. DNN allows users to define module titles using a rich text editor. Rich text fields permit HTML markup to support formatting. The platform fails to strip or neutralize executable script content from this input under specific rendering paths. When a victim loads a page containing the malicious module title, the embedded script executes in the victim's session context.

Exploitation requires an authenticated user with permission to edit module properties. User interaction is needed because the payload triggers only when a user views the page hosting the affected module. The scope is changed because script execution crosses from the editor's context into the viewer's browser security context.

Root Cause

The root cause is improper neutralization of input during web page generation. DNN's rich text handling for module titles preserves HTML elements such as <script> tags or event-handler attributes rather than enforcing an allowlist of safe formatting tags. The sanitization gap allows arbitrary JavaScript to persist in the database and reach the rendered DOM.

Attack Vector

An attacker with module-editing rights opens the module settings interface and submits a crafted title containing JavaScript through the rich text editor. The payload is stored server-side. Any authenticated or anonymous user who later browses the affected page triggers script execution. The attacker can capture cookies, abuse the victim's privileges through the DNN API, or pivot toward administrative account takeover.

Review the DNN Security Advisory GHSA-w9pf-h6m6-v89h for vendor-supplied technical details.

Detection Methods for CVE-2026-24838

Indicators of Compromise

• Module title fields containing <script> tags, javascript: URIs, or event-handler attributes such as onerror or onload
• Unexpected outbound requests from user browsers to attacker-controlled domains shortly after loading DNN pages
• Audit log entries showing module configuration edits by accounts that do not normally administer content

Detection Strategies

• Query the DNN content database for module titles containing HTML control characters or script-related substrings
• Monitor web server response bodies for unsanitized script content originating from module title fields
• Correlate page-view telemetry with browser-side errors or content security policy (CSP) violation reports

Monitoring Recommendations

• Enable verbose audit logging on DNN module edit events and forward to a centralized log platform
• Alert on bursts of module property changes from a single user or IP address
• Deploy a strict CSP and capture violation reports to flag inline script execution attempts

How to Mitigate CVE-2026-24838

Immediate Actions Required

• Upgrade DNN Platform installations to version 9.13.10 or 10.2.0 or later without delay
• Review module title fields across all portals for stored payloads and remove malicious content
• Audit accounts with module editing permissions and revoke access that is no longer required
• Rotate session secrets and force re-authentication after remediation to invalidate any stolen tokens

Patch Information

The DNN project released fixes in versions 9.13.10 and 10.2.0. Both releases sanitize module title rich text to prevent script execution. Refer to the DNN Security Advisory GHSA-w9pf-h6m6-v89h for download links and upgrade notes.

Workarounds

• Restrict module editing privileges to a minimal set of trusted administrators until patching is complete
• Apply a Content Security Policy that disallows inline scripts to limit the impact of injected payloads
• Use a web application firewall rule to block requests containing script tags in module title parameters

# Example CSP header to mitigate inline script execution
Content-Security-Policy: default-src 'self'; script-src 'self'; object-src 'none'; base-uri 'self'; report-uri /csp-report