CVE-2026-55230 in Vvveb
Summary
by MITRE • 10/01/2026
Vvveb is a powerful and easy to use CMS with page builder to build websites, blogs or ecommerce stores. Prior to version 1.0.8.6, Vvveb's HTML sanitizer fails to strip event-handler attributes when a tag carries a greater-than character inside a quoted attribute value. A low-privilege content author (default role author or contributor) can store a payload in post or product content that runs JavaScript in a browser of every visitor and of any administrator who views or previews that content, which opens a path to admin account takeover. This issue has been patched in version 1.0.8.6.
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Analysis
by VulDB Data Team • 10/01/2026
Vvveb is a widely utilized content management system designed for creating websites, blogs, and e-commerce stores through an intuitive page builder interface. The software allows users with varying levels of access to create and manage digital content. However, prior to version 1.0.8.6, the platform contained a critical security flaw within its HTML sanitization logic that undermined the integrity of stored data and exposed user sessions to malicious exploitation. This vulnerability specifically affects how the system processes HTML tags when they contain specific characters within attribute values, leading to a breakdown in input validation mechanisms.
The technical root cause of this vulnerability lies in the improper handling of greater-than characters enclosed within quoted attribute values during the sanitization process. The HTML sanitizer is designed to strip dangerous event-handler attributes such as onerror or onload which are commonly used in cross-site scripting attacks. However, when a tag includes a greater-than symbol inside a quoted string, the parser incorrectly interprets the structure of the HTML element. This parsing error causes the sanitizer to fail in identifying and removing subsequent malicious attributes that follow the malformed section. Consequently, what should have been stripped as dangerous code is instead preserved and rendered by the browser.
This flaw enables low-privilege users, such as those with author or contributor roles which are default access levels for many content creators, to inject persistent cross-site scripting payloads into posts or product descriptions. Because these entries are stored in the database rather than being transient session data, the malicious script executes every time a user views or previews that specific piece of content. This includes not only regular visitors but also administrators who review drafts or preview changes before publishing. The persistence of this payload means that even if the original attacker is removed from the system, the threat remains active as long as the compromised content exists in the database.
The operational impact of this vulnerability extends far beyond simple defacement or cookie theft. Since administrative accounts frequently view and edit content created by lower-privilege users, an administrator viewing a post containing the malicious payload will inadvertently execute the script within their own browser session under their elevated privileges. This effectively bypasses role-based access controls and opens a direct path to account takeover. An attacker can leverage this execution context to perform actions on behalf of the administrator, such as creating new admin accounts, modifying site configurations, or exfiltrating sensitive data from the backend system.
From an industry standards perspective, this vulnerability is classified under CWE-79, which covers Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. Specifically, it represents a stored variant where malicious scripts are permanently embedded within web application data. In terms of offensive security frameworks like MITRE ATT&CK, this aligns with techniques involving client-side code injection and potential privilege escalation through session hijacking or credential theft via script execution in an administrative context. The failure to properly sanitize input based on complex parsing edge cases highlights a gap in the defense-in-depth strategy typically expected from enterprise-grade CMS platforms.
To mitigate this risk, organizations using Vvveb must immediately upgrade to version 1.0.8.6 or later where the HTML sanitizer logic has been corrected to handle quoted attributes containing special characters correctly. Until an upgrade is performed, administrators should exercise extreme caution when previewing content authored by low-privilege users and consider implementing additional web application firewall rules that detect anomalous HTML structures indicative of this specific parsing bypass. Regular security audits and penetration testing focused on input validation edge cases are also recommended to identify similar vulnerabilities in other components of the platform.