CVE-2026-81778 in Kalles Addons Plugin
Summary
by MITRE • 08/31/2026
Subscriber Cross Site Scripting (XSS) in Kalles Addons <= 1.0.6 versions.
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Analysis
by VulDB Data Team • 08/31/2026
The vulnerability identified as Subscriber Cross-Site Scripting within the Kalles Addons plugin for WordPress, affecting versions up to and including 1.0.6, represents a significant security risk stemming from insufficient input validation and output encoding mechanisms. This flaw allows authenticated users with subscriber-level privileges to inject malicious JavaScript code into web pages viewed by other users or potentially even themselves in contexts where the injected script is executed within the browser's context of the vulnerable application. The core technical issue lies in the plugin’s failure to properly sanitize user-supplied data before rendering it on dynamic pages, thereby violating fundamental principles of secure coding practices that dictate all untrusted input must be treated as hostile until proven otherwise through rigorous validation and encoding processes.
From a technical perspective, this vulnerability is classified under CWE-79, which denotes Improper Neutralization of Input During Web Page Generation commonly known as Cross-Site Scripting. The attack vector typically involves an attacker crafting a malicious payload containing JavaScript code or HTML elements that exploit the lack of sanitization in specific input fields handled by the Kalles Addons plugin. When this crafted data is submitted to the server and subsequently stored or reflected back into the user interface without proper encoding, it becomes executable within the victim’s browser session. This execution context allows the malicious script to access cookies, local storage tokens, session identifiers, and other sensitive information associated with the current domain, effectively bypassing same-origin policies that are designed to isolate web applications from one another.
The operational impact of this vulnerability is substantial given its low privilege requirement for exploitation. Since only subscriber-level authentication is needed to trigger the flaw, a large number of potential attackers can leverage this weakness without needing elevated administrative rights. Successful exploitation can lead to account hijacking through session cookie theft, allowing an attacker to impersonate legitimate users and perform actions on their behalf such as modifying settings, accessing private data, or making unauthorized transactions if supported by the platform. Furthermore, persistent XSS attacks stored in database records could affect multiple victims over time, leading to widespread compromise of user accounts and potential defacement of public-facing pages where the malicious content is displayed.
In alignment with industry frameworks, this vulnerability maps directly to MITRE ATT&CK technique T1059.007, which covers JavaScript as a client-side scripting language used for automated execution within web browsers. The exploitation path often involves phishing or social engineering tactics to lure victims into clicking malicious links containing the XSS payload, aligning with initial access techniques that rely on user interaction rather than direct system intrusion. This highlights the importance of not only securing backend systems but also ensuring robust client-side defenses against script injection attacks that target end-users directly through compromised web applications.
Mitigation strategies must focus primarily on immediate patching and long-term secure development practices. Administrators running Kalles Addons versions 1.0.6 or earlier should upgrade to the latest patched version immediately, as developers typically release updates addressing known vulnerabilities by implementing proper input sanitization functions such as wp_kses_post in WordPress environments, which strips out dangerous HTML tags and attributes while preserving safe formatting. Additionally, enabling Content Security Policy headers can provide an additional layer of defense by restricting the sources from which scripts are allowed to load and execute, thereby mitigating the impact even if some injection attempts succeed. Regular security audits and code reviews focusing on input handling routines across all plugins integrated into the WordPress ecosystem will further reduce exposure to similar cross-site scripting risks in future deployments.