Overview
A reflected Cross-Site Scripting (XSS) vulnerability has been identified in the Clik Stats WordPress plugin. This vulnerability, tracked as CVE-2025-13513, affects all versions of the plugin up to and including version 0.8. Unauthenticated attackers can exploit this flaw to inject arbitrary web scripts into pages viewed by users if they can successfully trick a user into performing an action such as clicking on a malicious link.
Technical Details
The vulnerability stems from insufficient input sanitization and output escaping of the $_SERVER['PHP_SELF'] parameter within the plugin’s code. Specifically, the vulnerable code resides in the ck_admin.php file. An attacker can craft a malicious URL containing JavaScript code within the $_SERVER['PHP_SELF'] parameter. When a user clicks on this crafted URL, the unsanitized input is reflected back in the page’s HTML, allowing the injected JavaScript to execute within the user’s browser. This can lead to session hijacking, defacement, or other malicious activities.
You can examine the affected code segments in the following locations (though upgrading is highly recommended rather than attempting manual patching):
CVSS Analysis
The Common Vulnerability Scoring System (CVSS) score for CVE-2025-13513 is 6.1, classifying it as a MEDIUM severity vulnerability. The CVSS vector is likely something like CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N, meaning:
- AV:N (Attack Vector: Network): The vulnerability is exploitable over the network.
- AC:L (Attack Complexity: Low): The attack complexity is low.
- PR:N (Privileges Required: None): No privileges are required to exploit the vulnerability.
- UI:R (User Interaction: Required): User interaction is required to exploit the vulnerability (e.g., clicking on a link).
- S:C (Scope: Changed): The vulnerability can cause a change in scope (e.g., executing code in the context of another user).
- C:L (Confidentiality: Low): The vulnerability can lead to limited disclosure of confidential information.
- I:L (Integrity: Low): The vulnerability can lead to limited modification of data.
- A:N (Availability: None): The vulnerability does not affect the availability of the system.
Possible Impact
Exploitation of this XSS vulnerability could allow an attacker to:
- Steal sensitive information, such as user session cookies.
- Deface the affected website.
- Redirect users to malicious websites.
- Execute arbitrary code in the victim’s browser, potentially leading to further compromise of their system.
- Administer the WordPress site by using the identity of the logged-in admin user.
Mitigation and Patch Steps
The primary mitigation step is to update the Clik Stats plugin to the latest version, if one is available that addresses the vulnerability. Check the WordPress plugin repository or the plugin developer’s website for updates.
If an update is not available, consider the following temporary workarounds (though they are not ideal replacements for a proper patch):
- Deactivate the Clik Stats plugin: If you are not actively using the plugin, deactivating it will prevent the vulnerability from being exploited.
- Implement a Web Application Firewall (WAF): A WAF can help to filter out malicious requests and block attempts to exploit the XSS vulnerability. Configure the WAF with rules to block requests containing suspicious JavaScript code in the
$_SERVER['PHP_SELF']parameter.
