CVE-2023-6486 in Spectra Plugin
Summary
by MITRE • 04/09/2024
The Spectra – WordPress Gutenberg Blocks plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the Custom CSS metabox in all versions up to and including 2.10.3 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, 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 • 04/14/2026
The CVE-2023-6486 vulnerability affects the Spectra WordPress Gutenberg Blocks plugin, a popular tool for creating custom layouts and designs within WordPress environments. This plugin has been widely adopted by WordPress users seeking enhanced page building capabilities through the Gutenberg editor interface. The vulnerability specifically targets the Custom CSS metabox functionality within the plugin's administrative interface, representing a critical security flaw that undermines the integrity of WordPress sites using this particular plugin version.
The technical flaw stems from inadequate input sanitization and output escaping mechanisms within the plugin's codebase. When authenticated users with contributor-level privileges or higher attempt to save custom CSS content through the metabox interface, the plugin fails to properly validate or sanitize the input data before storing it in the WordPress database. This insufficient sanitization creates a persistent cross-site scripting vulnerability where malicious scripts can be stored and executed whenever the affected pages are loaded by other users. The vulnerability exists because the plugin does not implement proper HTML entity encoding or input validation before persisting user-supplied CSS content to the database.
The operational impact of this vulnerability is significant for WordPress administrators and site owners who rely on the Spectra plugin for their website functionality. Attackers with contributor-level access can leverage this vulnerability to execute arbitrary JavaScript code in the context of any user who visits pages containing the injected scripts. This could lead to session hijacking, credential theft, data exfiltration, or the redirection of users to malicious websites. The vulnerability is particularly dangerous because it requires minimal privileges to exploit, making it accessible to users who typically have limited administrative capabilities within WordPress. The stored nature of the XSS vulnerability means that the malicious scripts persist in the database and execute automatically whenever affected pages are accessed, creating a persistent threat vector that could remain undetected for extended periods.
Organizations should immediately update to the latest version of the Spectra plugin where this vulnerability has been addressed through proper input sanitization and output escaping mechanisms. The fix typically involves implementing comprehensive input validation that rejects potentially malicious CSS content and ensures proper HTML entity encoding before storing data in the database. System administrators should also consider implementing additional security measures such as content security policies, regular security audits of installed plugins, and monitoring for unauthorized changes to plugin files. This vulnerability aligns with CWE-79 which describes Cross-Site Scripting flaws, and represents a clear violation of the principle of least privilege as it allows users with minimal permissions to execute code with broader system access. The ATT&CK framework categorizes this vulnerability under T1059.007 for Scripting and T1566.001 for Phishing, as it enables attackers to deliver malicious payloads through compromised WordPress installations. Organizations should also review their WordPress plugin management policies to ensure timely updates and maintain comprehensive security monitoring across all installed plugins to prevent exploitation of similar vulnerabilities in other third-party components.