CVE-2019-25734: Contact Form by WD CSRF & Local File Inclusion Vulnerability

Technical summary

CVE-2019-25734 affects Contact Form by WD 1.13.1 and involves an improper neutralization of special elements used in a file path (CWE-22). The vulnerability chains a CSRF attack with LFI by exploiting unsanitized action parameters in requests to admin-ajax.php. Attackers craft requests containing directory traversal sequences (e.g., ../) in the GET action parameter, which the plugin fails to validate. When an authenticated administrator visits a page hosting the malicious form, the CSRF component causes their browser to submit the request, and the LFI component allows the plugin to include arbitrary files from the server filesystem without proper access controls.

Business impact

An attacker exploiting this vulnerability can read sensitive files stored on the WordPress server, such as configuration files containing database credentials, private keys, or other confidential data. While the CVSS score is MEDIUM (4.0), the integrity impact and reliance on social engineering (admin interaction) limit the severity. However, information disclosure poses a genuine risk to organizations relying on this plugin for form functionality, as compromised credentials could enable lateral movement or further attacks.

Affected systems

Contact Form by WD version 1.13.1 is affected. Organizations using this WordPress plugin in production should verify their deployed version. Administrators and developers responsible for WordPress plugin inventory should identify instances of Contact Form by WD and assess whether they are running 1.13.1 or earlier versions. The vulnerability requires an authenticated administrator to visit a malicious link, so exposure is limited to admin-level WordPress users.

Exploitability

Exploitation requires social engineering to trick an administrator into visiting or interacting with a malicious form. The vulnerability is not remotely exploitable without user interaction, and the attacker cannot force execution. The local attack vector (as indicated by the CVSS vector) suggests the primary risk involves servers where an attacker may have limited local access or the ability to host malicious content that admins might visit. The CVSS score of 4.0 reflects the relatively low base exploitability when accounting for user interaction requirements.

Remediation

Immediately update Contact Form by WD to a patched version released after 1.13.1. Verify the specific version number and release notes against the vendor's official advisory before deployment. As an interim measure, disable the plugin if it is not actively in use, or restrict admin-ajax.php access to known administrative IP ranges using firewall rules or WordPress security plugins. Audit server logs for suspicious requests containing directory traversal sequences targeting admin-ajax.php.

Patch guidance

Check the Contact Form by WD plugin repository or vendor website for a security update addressing CVE-2019-25734. Apply the patch to all affected WordPress installations as soon as available. Test the update in a staging environment first to confirm compatibility with your WordPress version and other plugins. Enable automatic updates for this plugin if your WordPress environment supports it. Document the patch version applied for compliance and inventory purposes.

Detection guidance

Monitor web server and WordPress logs for requests to admin-ajax.php containing directory traversal patterns in the action parameter (e.g., %2e%2e%2f or ../). Use Web Application Firewall (WAF) rules to block requests with unencoded or encoded traversal sequences in query parameters. Deploy WordPress security plugins that can detect and log suspicious AJAX requests. Regular vulnerability scanning of WordPress plugins can identify outdated versions of Contact Form by WD before exploitation occurs.

Why prioritize this

Although the CVSS score is MEDIUM (4.0), this vulnerability should be prioritized for remediation because it enables information disclosure of potentially sensitive files. The exploitation chain, while requiring admin interaction, is straightforward to execute. Organizations with Contact Form by WD installed should treat this as a moderate-priority patch. The fact that it is not yet listed on the Known Exploited Vulnerabilities (KEV) catalog does not diminish its importance—early patching reduces exposure before public exploit code emerges.

Risk score, explained

The CVSS 3.1 score of 4.0 (MEDIUM) reflects an attack vector limited to the local scope (AV:L), low attack complexity (AC:L), no privilege requirements (PR:N), and no user interaction strictly required from a technical standpoint (UI:N). However, in practice, the CSRF component necessitates admin interaction. The score accounts for low integrity impact (I:L) with no confidentiality or availability damage in the base vector. Organizations should contextualize this score within their own risk tolerance; file inclusion vulnerabilities can be more dangerous if sensitive configuration files are accessible.

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