CVE-2025-2918 in Ultimate Blocks Plugin
Summary
by MITRE • 06/10/2025
The Ultimate Blocks – WordPress Blocks Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via multiple widgets in all versions up to, and including, 3.3.3 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 • 06/10/2025
The Ultimate Blocks plugin for WordPress represents a significant security vulnerability through its susceptibility to stored cross-site scripting attacks affecting all versions up to and including 3.3.3. This flaw resides within the plugin's handling of multiple widgets where insufficient input sanitization and output escaping mechanisms fail to properly validate or escape user-supplied data. The vulnerability specifically targets authenticated attackers who possess Contributor-level access or higher privileges within the WordPress environment, making it particularly concerning as it leverages legitimate user permissions to execute malicious code.
The technical implementation of this vulnerability stems from the plugin's failure to adequately sanitize user inputs across various widget components. When contributors or higher-privileged users create or modify content through these widgets, the plugin does not sufficiently validate or escape the data before storing it in the database. This stored data then gets executed whenever any user accesses pages containing the injected scripts, creating a persistent threat vector that can affect all visitors to the compromised WordPress site. The flaw operates as a classic stored XSS vulnerability where malicious payloads are saved server-side and executed client-side without requiring additional user interaction beyond visiting affected pages.
The operational impact of this vulnerability extends beyond simple script injection, potentially enabling attackers to escalate privileges, steal session cookies, perform unauthorized actions within the WordPress admin interface, or redirect users to malicious websites. Since Contributors typically have the ability to publish posts and edit their own content, an attacker with these credentials could compromise the entire site by injecting scripts that target other users with higher privileges. The vulnerability creates a persistent threat that remains active until the malicious code is removed from the database, making it particularly dangerous in multi-user environments where multiple contributors may be involved.
Mitigation strategies should focus on immediate plugin updates to versions that address the sanitization and escaping deficiencies, though administrators must first verify that updated versions properly resolve all affected widgets. Security hardening measures including input validation at multiple layers, output escaping for all dynamic content, and regular security audits of plugin components can help prevent similar vulnerabilities. The flaw aligns with CWE-79 which specifically addresses cross-site scripting vulnerabilities, and follows patterns consistent with ATT&CK technique T1548.003 related to account access and privilege escalation through web application vulnerabilities. Organizations should implement comprehensive monitoring for unusual contributor activity and maintain regular security assessments of all WordPress plugins to prevent exploitation of similar input validation weaknesses that could compromise the broader web application ecosystem.