CVE-2025-6024: Authentication Endpoint XSS Vulnerability

CVE-2025-6024 Overview

CVE-2025-6024 is a Cross-Site Scripting (XSS) vulnerability affecting the authentication endpoint of WSO2 products. The vulnerability occurs because the authentication endpoint fails to encode user-supplied input before rendering it in the web page, allowing attackers to inject malicious scripts into the application.

An attacker can leverage this vulnerability by injecting malicious scripts into the authentication endpoint. This can result in the user's browser being redirected to a malicious website, manipulation of the web page's user interface, or the retrieval of information from the browser. However, session hijacking is not possible due to the httpOnly flag protecting session-related cookies.

Critical Impact

Attackers can inject malicious JavaScript into the authentication endpoint, potentially redirecting users to malicious sites, manipulating the UI for phishing attacks, or exfiltrating sensitive browser information.

Affected Products

• WSO2 Products (specific versions detailed in the security advisory)

Discovery Timeline

• April 16, 2026 - CVE CVE-2025-6024 published to NVD
• April 16, 2026 - Last updated in NVD database

Technical Details for CVE-2025-6024

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting or XSS. The authentication endpoint in affected WSO2 products accepts user-supplied input and renders it directly into the HTML response without proper encoding or sanitization.

When user input containing JavaScript or HTML markup is submitted to the authentication endpoint, the application fails to escape special characters such as <, >, ", and '. This allows the injected content to be interpreted as executable code by the victim's browser rather than being displayed as plain text.

The scope of the vulnerability allows for cross-origin impact, meaning malicious scripts can access resources beyond the vulnerable application's origin under certain conditions. While the httpOnly flag on session cookies prevents direct session token theft, attackers can still perform various malicious actions including credential harvesting through fake login forms, keylogging, and browser fingerprinting.

Root Cause

The root cause of this vulnerability lies in improper output encoding within the authentication endpoint's response generation logic. When the application constructs HTML responses, it directly concatenates user-supplied parameters without applying context-appropriate encoding functions. This violates the fundamental security principle of treating all user input as untrusted and encoding it before output.

The authentication endpoint should apply HTML entity encoding for content rendered in HTML body context, JavaScript encoding for content rendered within script blocks, and URL encoding for content rendered in URL attributes.

Attack Vector

The attack vector for this vulnerability is network-based and requires user interaction. An attacker must craft a malicious URL containing JavaScript payload in a vulnerable parameter and trick a victim into clicking the link. This is typically accomplished through phishing emails, malicious advertisements, or compromised websites that redirect users to the crafted URL.

When the victim visits the malicious URL while authenticated to the WSO2 application, the injected script executes in the context of their session. The script can then perform actions on behalf of the user, steal sensitive information displayed on the page, or redirect the user to an attacker-controlled site designed to harvest credentials.

Detection Methods for CVE-2025-6024

Indicators of Compromise

• Unusual URL parameters containing JavaScript keywords such as <script>, javascript:, onerror, or onload in authentication endpoint requests
• Web application firewall logs showing blocked XSS patterns targeting authentication URLs
• User reports of unexpected redirects or UI anomalies when accessing the authentication page
• Browser console errors indicating blocked inline script execution due to Content Security Policy violations

Detection Strategies

• Deploy web application firewall rules to detect and block common XSS patterns in URL parameters and request bodies
• Enable verbose logging on the authentication endpoint to capture full request URLs including query parameters
• Implement Content Security Policy headers with strict inline script restrictions to detect and prevent XSS execution
• Monitor for anomalous authentication endpoint access patterns, particularly URLs with encoded special characters

Monitoring Recommendations

• Configure SIEM rules to alert on authentication endpoint requests containing common XSS payload signatures
• Establish baseline metrics for authentication endpoint traffic patterns to identify anomalies
• Review web server access logs regularly for suspicious parameter values in authentication-related URLs
• Implement browser-side monitoring to detect unexpected script execution in authentication workflows

How to Mitigate CVE-2025-6024

Immediate Actions Required

• Review the WSO2 Security Advisory WSO2-2025-4251 for specific patch information and affected versions
• Apply vendor-provided security patches to all affected WSO2 installations immediately
• Implement Content Security Policy headers to provide defense-in-depth against XSS attacks
• Conduct a security review of any customizations made to the authentication endpoint

Patch Information

WSO2 has released security updates addressing this vulnerability. Administrators should consult the WSO2 Security Advisory WSO2-2025-4251 for detailed patching instructions, affected version information, and download links for the security fixes.

Organizations should prioritize patching internet-facing WSO2 deployments and those handling sensitive authentication workflows. After applying patches, verify the fix by testing the authentication endpoint with benign XSS test payloads to confirm proper input encoding.

Workarounds

• Deploy a web application firewall in front of the authentication endpoint to filter malicious input until patches can be applied
• Implement strict Content Security Policy headers with script-src 'self' to prevent inline script execution
• Consider restricting access to the authentication endpoint to trusted IP ranges where feasible
• Enable additional logging and monitoring on authentication endpoints to detect exploitation attempts

# Example Content Security Policy header configuration for Apache
# Add to httpd.conf or .htaccess
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; frame-ancestors 'self';"