CVE-2026-3003 in Booking Widget Plugin
Summary
by MITRE • 03/21/2026
The Vagaro Booking Widget plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘vagaro_code’ parameter in all versions up to, and including, 0.3 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Analysis
by VulDB Data Team • 03/21/2026
The Vagaro Booking Widget plugin for WordPress represents a critical security vulnerability classified as CVE-2026-3003, affecting all versions up to and including 0.3. This vulnerability stems from insufficient input sanitization and output escaping mechanisms within the plugin's handling of the 'vagaro_code' parameter, creating a persistent cross-site scripting attack vector that can be exploited by unauthenticated threat actors. The flaw exists in the plugin's core architecture where user-supplied input fails to undergo proper validation before being processed and rendered within the web application's output, violating fundamental security principles of input sanitization and output encoding.
The technical implementation of this vulnerability allows attackers to inject malicious JavaScript code through the 'vagaro_code' parameter, which is then stored within the plugin's data handling mechanisms. When legitimate users access pages containing this injected content, the stored script executes in their browser context, creating a persistent XSS attack scenario. This type of vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws where applications fail to properly validate or escape user-controllable data before incorporating it into dynamically generated web pages. The vulnerability's persistence stems from the fact that the malicious code is stored server-side rather than being reflected in a single request, making it particularly dangerous as it can affect multiple users over time.
The operational impact of this vulnerability extends beyond simple script execution, as it creates a potential attack surface for more sophisticated malicious activities. An attacker could leverage this vulnerability to steal user session cookies, redirect victims to malicious websites, perform actions on behalf of authenticated users, or even escalate privileges within the WordPress environment. The unauthenticated nature of the attack means that any user visiting a compromised page could become victim to the injected scripts, making this vulnerability particularly dangerous in environments where the plugin is widely used or where users have varying levels of security awareness. This aligns with ATT&CK technique T1566.001 which covers the use of malicious HTML files to execute code on target systems, and represents a classic example of how web application vulnerabilities can be exploited to establish persistent footholds within target environments.
Mitigation strategies for CVE-2026-3003 should prioritize immediate plugin updates to versions that address the input sanitization and output escaping deficiencies. System administrators should implement comprehensive input validation measures that filter and sanitize all user-supplied data before processing, ensuring that any potentially malicious content is neutralized before storage or rendering. The implementation of Content Security Policy headers can provide additional protection layers by restricting script execution sources and preventing unauthorized code injection. Regular security audits of WordPress plugins and themes should be conducted to identify similar vulnerabilities, with particular attention to input handling mechanisms and output encoding practices. Organizations should also consider implementing web application firewalls to detect and block suspicious parameter values, while maintaining updated security monitoring systems to identify potential exploitation attempts. The vulnerability highlights the importance of adhering to secure coding practices and following established security frameworks such as the OWASP Top Ten to prevent similar issues in future development cycles.