CVE-2020-35930

Step 1: Authentication: The attacker must first authenticate to the Seo Panel application, likely by obtaining valid credentials or exploiting another vulnerability.

Step 2: Payload Injection: The attacker crafts a malicious JavaScript payload (e.g., <script>alert('XSS')</script>) and injects it into the url parameter when creating or modifying a website entry via the seo/seopanel/websites.php URI.

Step 3: Payload Storage: The application stores the injected payload in the database, without proper sanitization.

Step 4: Victim Interaction: A legitimate user, with appropriate permissions, views the website information, which includes the attacker-controlled url parameter.

Step 5: Payload Execution: The browser renders the stored url parameter, executing the malicious JavaScript payload within the user's browser context.

The vulnerability stems from insufficient input validation and output encoding of the url parameter within the seo/seopanel/websites.php URI. Specifically, the application fails to properly sanitize user-supplied input before storing it in the database and subsequently rendering it in the browser. This allows an attacker to inject malicious JavaScript code into the url parameter. When a legitimate user views the website information, the injected JavaScript executes within their browser, enabling the attacker to steal cookies, redirect users, or perform other malicious actions. The root cause is a lack of HTML encoding or input validation on the url parameter before storage and retrieval.