CVE-2025-61674 Overview
A Cross-Site Scripting (XSS) vulnerability has been identified in October CMS, a popular Content Management System (CMS) and web platform. Prior to versions 3.7.13 and 4.0.12, the backend configuration forms are susceptible to XSS attacks. A user with the Global Editor Settings permission can inject malicious HTML/JavaScript into the stylesheet input at Markup Styles. A specially crafted input can break out of the intended <style> context, allowing arbitrary script execution across backend pages for all users.
Critical Impact
Attackers with Global Editor Settings permission can execute arbitrary JavaScript in the browsers of all backend users, potentially leading to session hijacking, credential theft, and administrative account compromise.
Affected Products
- October CMS versions prior to 3.7.13
- October CMS versions prior to 4.0.12
Discovery Timeline
- 2026-01-10 - CVE CVE-2025-61674 published to NVD
- 2026-01-13 - Last updated in NVD database
Technical Details for CVE-2025-61674
Vulnerability Analysis
This vulnerability is classified as CWE-79 (Cross-Site Scripting), specifically a stored XSS vulnerability affecting the October CMS backend. The flaw exists in the Markup Styles configuration area where administrators with Global Editor Settings permission can input custom stylesheets. The application fails to properly sanitize or escape user-supplied content before rendering it within a <style> HTML context.
When malicious input is submitted through the stylesheet configuration, the attacker can break out of the <style> tags entirely. This allows injection of arbitrary HTML and JavaScript that executes in the context of any backend user's session who accesses the affected pages. Since this is a stored XSS vulnerability, the malicious payload persists in the application database and affects all users viewing the compromised backend pages.
The vulnerability requires authentication and specific permissions (Global Editor Settings), which limits the attack surface. However, the impact is significant because successful exploitation affects all backend users, including those with higher privileges than the attacker.
Root Cause
The root cause of this vulnerability is insufficient input validation and output encoding in the Markup Styles functionality. When user-supplied stylesheet content is processed and rendered, the application does not adequately sanitize special characters that could break out of the intended <style> element context. This allows an attacker to close the style tag and inject arbitrary HTML elements including script tags.
Attack Vector
The attack requires network access and is performed through the October CMS web interface. An authenticated attacker with Global Editor Settings permission navigates to the Markup Styles configuration area and submits a specially crafted payload designed to escape the <style> context. The payload typically includes closing style tags followed by script elements containing malicious JavaScript.
Once the payload is saved, it becomes persistent in the application. Any backend user who subsequently loads pages that render the Markup Styles configuration will have the malicious JavaScript execute in their browser context. This can be leveraged to steal session cookies, perform actions on behalf of the victim user, or exfiltrate sensitive data from the administrative interface.
Detection Methods for CVE-2025-61674
Indicators of Compromise
- Unusual or obfuscated content in Markup Styles configuration containing </style> tags or <script> elements
- Backend JavaScript errors or unexpected script execution in browser developer tools
- Database entries in stylesheet configuration containing HTML tags outside of valid CSS syntax
- Audit logs showing modifications to Global Editor Settings by unauthorized or suspicious users
Detection Strategies
- Monitor backend configuration changes for suspicious patterns including HTML tags in stylesheet fields
- Implement Content Security Policy (CSP) headers to detect and block inline script execution attempts
- Review web application firewall (WAF) logs for XSS payload signatures in POST requests to configuration endpoints
- Conduct regular audits of users with Global Editor Settings permissions and their recent activities
Monitoring Recommendations
- Enable detailed audit logging for all backend configuration changes in October CMS
- Set up alerts for any modifications to Markup Styles settings
- Monitor browser console errors across backend pages that may indicate XSS payload execution failures
- Implement file integrity monitoring on configuration templates and database entries
How to Mitigate CVE-2025-61674
Immediate Actions Required
- Upgrade October CMS to version 3.7.13 or 4.0.12 or later immediately
- Review and audit all users with Global Editor Settings permission and restrict access where unnecessary
- Inspect current Markup Styles configuration for any suspicious or malicious content
- Clear browser caches for all backend users after applying the patch
Patch Information
This vulnerability has been patched in October CMS versions 3.7.13 and 4.0.12. Users should update to these versions or later to remediate the issue. The security advisory with detailed patch information is available at the GitHub Security Advisory.
Workarounds
- Temporarily revoke Global Editor Settings permission from all non-essential users until the patch is applied
- Implement a Web Application Firewall (WAF) rule to block requests containing </style> or <script> patterns in configuration form submissions
- Manually review and sanitize any existing Markup Styles entries for HTML content
- Enable strict Content Security Policy headers to mitigate the impact of any successful XSS exploitation
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
