CVE-2026-28568 in Quill Forms Plugin
Summary
by MITRE • 08/18/2026
Unauthenticated Cross Site Scripting (XSS) in Quill Forms <= 5.7.1 versions.
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Analysis
by VulDB Data Team • 08/18/2026
The vulnerability identified as an unauthenticated cross-site scripting flaw within the Quill Forms plugin for WordPress, affecting version 5.7.1 and earlier, represents a significant security risk to web applications relying on this software for data collection and form management. Cross-site scripting is a persistent injection attack where malicious scripts are injected into otherwise benign and trusted websites. In this specific context, the lack of authentication required to exploit the vulnerability means that any user with access to the public-facing website can potentially execute arbitrary JavaScript code in the browsers of other users who visit the affected pages or interact with compromised forms. This absence of an authorization gate drastically lowers the barrier for entry, allowing attackers from anywhere on the internet to initiate exploitation without needing valid credentials or prior interaction with a privileged account.
The technical root cause typically involves insufficient sanitization and validation of user-supplied input before it is rendered in the web page's HTML output. When users submit data through Quill Forms fields such as name, email, message body, or custom form inputs, the application fails to properly escape special characters like angle brackets, quotes, and ampersands. Consequently, when this unsanitized data is displayed back to other visitors, the browser interprets the injected script tags as executable code rather than plain text. This behavior allows an attacker to craft a malicious payload that executes in the context of the victim's session. The impact extends beyond simple defacement; it enables session hijacking through cookie theft, keylogging to capture sensitive information such as passwords and credit card numbers, redirection to phishing sites, or even performing actions on behalf of the user if they have administrative privileges within the WordPress environment.
From a classification perspective, this vulnerability aligns with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. The specific nature of being unauthenticated places it firmly in the category of persistent or stored XSS if the malicious input is saved to the database and served later, though reflected variants are also possible depending on how the form handles submission feedback. In terms of offensive security frameworks, this exploit maps directly to MITRE ATT&CK technique T1059.007, which covers JavaScript execution within a browser environment. The attack vector leverages social engineering or direct link manipulation to trick users into visiting a compromised page where the script automatically executes upon load, facilitating data exfiltration without any user interaction beyond viewing the page.
The operational impact of this vulnerability is severe for both site administrators and end-users. For administrators, it poses a risk of account takeover if an administrator visits a maliciously crafted form response or link while logged into their WordPress dashboard. This could lead to complete compromise of the website's backend, allowing further malware distribution, defacement, or use as part of a botnet. For regular users and customers filling out forms, the primary concern is privacy violation and financial loss through credential theft or payment fraud if sensitive data is entered into compromised fields. The trust associated with legitimate web forms is undermined, potentially damaging the reputation of the organization hosting the site and leading to non-compliance with data protection regulations such as GDPR or CCPA due to unauthorized access to personal identifiable information.
Mitigation strategies must be implemented immediately to address this critical flaw. The most effective solution is to upgrade the Quill Forms plugin to version 5.7.2 or later, where developers have presumably patched the input validation and output encoding mechanisms. If upgrading is not immediately feasible due to compatibility constraints with other plugins or themes, temporary workarounds should be considered. These include implementing a Web Application Firewall that can detect and block common XSS payloads in HTTP requests, although this is less reliable than code-level fixes. Additionally, administrators should ensure that Content Security Policy headers are configured on the server to restrict script execution sources, thereby limiting the impact of any successfully injected scripts by preventing them from loading external resources or executing inline unless explicitly allowed for trusted domains. Regular security audits and penetration testing of form submissions can also help identify similar vulnerabilities in custom code or other plugins before they are exploited in production environments.