CVE-2026-39768 in Security & Malware Scan Plugin
Summary
by MITRE • 10/06/2026
Unauthenticated Cross Site Scripting (XSS) in Security & Malware scan by CleanTalk <= 2.189 versions.
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Analysis
by VulDB Data Team • 10/06/2026
The vulnerability identified as an unauthenticated cross-site scripting flaw within the CleanTalk plugin for WordPress, specifically affecting versions up to and including 2.189, represents a significant security risk due to its lack of authentication requirements. This characteristic allows any remote attacker with network access to exploit the weakness without needing valid credentials or prior interaction with authenticated user sessions. The core technical issue stems from insufficient input validation and sanitization mechanisms within the plugin's handling of data related to Security & Malware scan functionalities. When user-supplied input is processed, it fails to properly neutralize special characters that have meaning in HTML contexts, thereby allowing malicious scripts to be injected into web pages viewed by other users or administrators.
From a technical perspective, this flaw aligns with CWE-79, which classifies improper neutralization of input during web page generation as Cross-site Scripting. The vulnerability likely exists because the application directly echoes user-controllable data back to the browser without applying appropriate encoding rules such as HTML entity encoding or context-aware output filtering. In many WordPress plugins, this often occurs in admin-facing interfaces where parameters are passed via GET or POST requests and rendered into dynamic content areas like dashboard widgets, status reports, or configuration panels. Because the vulnerability is unauthenticated, an attacker can craft a malicious URL containing embedded JavaScript payloads that trigger when loaded by a victim with administrative privileges who accesses the affected page.
The operational impact of this vulnerability extends beyond simple script execution. Successful exploitation enables attackers to perform session hijacking by stealing administrator cookies through document.cookie access, facilitating unauthorized control over the WordPress installation. It also allows for phishing attacks where fake login forms are injected into legitimate pages to capture credentials. Furthermore, persistent XSS variants could be achieved if user input is stored in a database and later rendered without sanitization, leading to long-term compromise of all visitors who view the infected content. The ability to execute arbitrary JavaScript opens pathways for defacement, data exfiltration from connected services, or pivoting into deeper network intrusions depending on the surrounding infrastructure's security posture.
This vulnerability maps directly to MITRE ATT&CK technique T1059.007, which covers Command and Scripting Interpreter via JavaScript within web applications. The attack vector is classified under Remote Code Execution prerequisites but specifically leverages client-side execution capabilities rather than server-side command injection. Attackers typically utilize social engineering tactics combined with the crafted malicious link to induce victims into triggering the payload. Once executed, the script operates in the context of the trusted domain associated with the WordPress site, bypassing same-origin policy restrictions and gaining elevated trust from browsers regarding data access permissions for that specific origin.
Mitigation strategies must prioritize immediate patching by upgrading CleanTalk to a version newer than 2.189 where these input validation issues have been addressed by developers through rigorous sanitization protocols. Until an update is applied, administrators should implement Web Application Firewall rules designed to detect and block common XSS payload patterns in HTTP request parameters. Additionally, enforcing strict Content Security Policy headers can significantly reduce the impact of successful exploitation by restricting script execution sources and preventing inline scripts from running unless explicitly whitelisted. Regular security audits focusing on input handling across all plugin endpoints are essential for maintaining robust defense-in-depth measures against similar injection-based threats prevalent in open-source ecosystems.