CVE-2026-3007: Koollab LMS Stored XSS Vulnerability

CVE-2026-3007 Overview

CVE-2026-3007 is a stored cross-site scripting (XSS) vulnerability affecting Koollab LMS' courselet feature. Successful exploitation of this vulnerability could allow an attacker to execute arbitrary JavaScript on any user account that has access to the courselet feature, potentially leading to session hijacking, credential theft, or malicious actions performed on behalf of authenticated users.

Critical Impact

Attackers can inject and persist malicious JavaScript code within the Koollab LMS courselet feature, enabling arbitrary script execution in the context of any user viewing the affected content.

Affected Products

• Koollab LMS (courselet feature)

Discovery Timeline

• 2026-04-23 - CVE CVE-2026-3007 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2026-3007

Vulnerability Analysis

This stored XSS vulnerability resides in the courselet feature of Koollab LMS, a learning management system. Unlike reflected XSS attacks, stored XSS vulnerabilities persist malicious payloads within the application's database, meaning any user who subsequently views the affected content will have the malicious script executed in their browser context.

The vulnerability requires an authenticated user with low privileges to inject the malicious payload, but the impact extends to all users who access the compromised courselet content. The scope is changed, meaning the vulnerable component and the impacted component are different—the injection occurs in the LMS backend, but the payload executes in victim browsers.

The attack can result in limited confidentiality and integrity impacts, allowing attackers to access session tokens, perform actions as the victim user, deface content, or redirect users to malicious sites.

Root Cause

The root cause of CVE-2026-3007 is improper input validation and output encoding in the Koollab LMS courselet feature. User-supplied input is stored in the application database without adequate sanitization and is later rendered in web pages without proper HTML encoding, allowing injected JavaScript to execute in victim browsers.

Attack Vector

The attack requires network access and a low-privileged authenticated account within the Koollab LMS platform. The attacker must inject malicious JavaScript through the courselet feature interface, which then persists in the application. When other users—including administrators—view the affected courselet content, the malicious script executes in their browser session.

The attack requires user interaction, as victims must navigate to and view the poisoned courselet content. However, in an educational LMS environment, courselets are routinely accessed by students and instructors, making successful exploitation highly probable once the payload is planted.

For technical details on this vulnerability, refer to the CSA Security Alert AL-2026-042.

Detection Methods for CVE-2026-3007

Indicators of Compromise

• Unusual JavaScript code or HTML tags appearing in courselet content fields within the Koollab LMS database
• Web server logs showing injection attempts with encoded script tags (<script>, javascript:, event handlers) in courselet-related POST requests
• User reports of unexpected browser behavior, pop-ups, or redirections when accessing courselet content

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block common XSS payloads in HTTP requests targeting the courselet feature
• Deploy content security policy (CSP) headers to restrict script execution and report violations
• Conduct regular security scanning of stored content in the LMS database to identify malicious script injections

Monitoring Recommendations

• Enable detailed logging of all content submissions and modifications within the courselet feature
• Monitor for CSP violation reports that may indicate attempted or successful XSS exploitation
• Review authentication logs for unusual account activity following potential XSS exploitation, such as password changes or privilege modifications

How to Mitigate CVE-2026-3007

Immediate Actions Required

• Review all existing courselet content for malicious JavaScript injection and sanitize any compromised entries
• Implement strict input validation on all user-supplied content in the courselet feature
• Apply output encoding (HTML entity encoding) when rendering user-generated content in web pages
• Consider restricting courselet content creation privileges while remediation is in progress

Patch Information

Refer to the CSA Security Alert AL-2026-042 for official vendor guidance and patch information. Organizations should apply any available security updates from the Koollab LMS vendor as soon as they become available.

Workarounds

• Deploy a web application firewall (WAF) with XSS filtering rules to block common injection patterns
• Implement Content Security Policy (CSP) headers with restrictive script-src directives to mitigate the impact of successful XSS attacks
• Temporarily disable or restrict access to the courselet feature for untrusted users until a vendor patch is applied
• Conduct manual review of all courselet content submissions before they are published to other users

# Example CSP header configuration to mitigate XSS impact
# Add to web server configuration (Apache example)
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'; base-uri 'self';"