CVE-2023-0096 in Happyforms Plugin
Summary
by MITRE • 02/06/2023
The Happyforms WordPress plugin before 1.22.0 does not validate and escape some of its block options before outputting them back in a page/post where the block is embed, which could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks.
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Analysis
by VulDB Data Team • 02/15/2023
The vulnerability identified as CVE-2023-0096 affects the Happyforms WordPress plugin version 1.22.0 and earlier, presenting a critical security risk through stored cross-site scripting exploits. This issue stems from insufficient input validation and output escaping mechanisms within the plugin's block handling functionality, creating a pathway for malicious actors to inject persistent malicious scripts into WordPress content. The vulnerability specifically targets the plugin's block options processing, where user-supplied data is not properly sanitized before being rendered back to the browser, enabling attackers to execute arbitrary JavaScript code within the context of other users' sessions.
The technical flaw manifests in the plugin's failure to adequately sanitize user inputs when processing block options, which are typically used to configure form elements within WordPress editor interfaces. This weakness allows authenticated users with contributor level privileges and above to submit malicious payloads through the form block configuration interface. When these crafted inputs are later rendered in the frontend or edited within the WordPress admin, the unescaped script content executes in the browsers of unsuspecting users who view the affected content. The vulnerability is classified under CWE-79 as a failure to escape output, specifically manifesting as stored XSS in a content management system environment. This type of vulnerability enables attackers to bypass standard security measures and persist their malicious code within the WordPress installation.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with significant capabilities to compromise user sessions, steal sensitive information, and potentially escalate privileges within the WordPress environment. Contributors and above roles in WordPress typically have substantial access rights including the ability to create and edit posts, which means that successful exploitation could lead to unauthorized content modification, data exfiltration, or even complete compromise of the WordPress installation. The stored nature of the XSS attack means that the malicious payload remains persistent and will execute every time the affected content is viewed, making it particularly dangerous for high-traffic websites where content is frequently accessed by multiple users. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1566 for phishing with malicious attachments and T1059 for command and scripting interpreter, as it enables attackers to establish persistent access through browser-based exploitation.
Mitigation strategies for CVE-2023-0096 primarily focus on immediate remediation through plugin updates to version 1.22.0 or later, which contain the necessary input validation and output escaping fixes. Organizations should also implement additional security measures including regular security audits of WordPress plugins, implementation of content security policies to limit script execution, and monitoring of user activity for suspicious content creation patterns. Network-level protections such as web application firewalls can provide additional defense-in-depth, though they should not be relied upon as the sole mitigation. Administrators should also consider implementing role-based access controls to limit the privileges of users who can create or modify form content, reducing the attack surface for potential exploitation. The vulnerability highlights the critical importance of proper input validation and output escaping in web applications, particularly in content management systems where user-generated content processing is common. Regular security assessments and prompt patch management are essential practices to prevent exploitation of similar vulnerabilities in WordPress plugin ecosystems.