CVE-2026-14494 Overview
CVE-2026-14494 is an unauthenticated remote code execution vulnerability in the Sigma Forms Pro plugin for WordPress. The flaw affects all plugin versions up to and including 1.4.5. The handle_form_submission function dynamically grants the unfiltered_upload capability to every user during form submissions. When allowed_file_types is not configured, the plugin bypasses MIME type validation entirely. Attackers can upload arbitrary PHP files and execute code on the server without authentication. Several bundled templates, including Job Application, Support Ticket, and Wholesale Application, ship with file upload fields that have no type restrictions by design. This makes affected installations exploitable immediately after activation.
Critical Impact
Unauthenticated attackers can upload arbitrary files and execute code on WordPress servers running Sigma Forms Pro 1.4.5 or earlier, leading to full site compromise.
Affected Products
- Sigma Forms Pro plugin for WordPress, all versions up to and including 1.4.5
- WordPress sites using default templates (Job Application, Support Ticket, Wholesale Application)
- WordPress installations where the plugin's handle_form_submission handler is reachable
Discovery Timeline
- 2026-08-29 - CVE-2026-14494 published to NVD
- 2026-08-31 - Last updated in NVD database
Technical Details for CVE-2026-14494
Vulnerability Analysis
The vulnerability is classified as an Unrestricted Upload of File with Dangerous Type [CWE-434]. The Sigma Forms Pro plugin exposes a form submission handler that accepts file uploads from unauthenticated visitors. During submission, the plugin elevates the effective user context by granting the WordPress unfiltered_upload capability. This capability normally restricts uploads to administrators on single-site installations. Granting it to anonymous submitters removes the primary safety boundary WordPress enforces on media uploads.
When a form does not define an allowed_file_types list, the plugin skips MIME type validation and extension checks. The uploaded file lands inside the WordPress uploads directory, where the web server executes PHP by default. Because several first-party templates ship with no file type restrictions, sites are exposed immediately upon installation without any misconfiguration by the administrator.
Root Cause
The root cause is a combination of insecure capability elevation and missing input validation. The handle_form_submission function grants privileged upload rights based on request context rather than authenticated user identity. It then defers file type enforcement to a configuration value that is unset in default templates, resulting in no validation at all.
Attack Vector
An unauthenticated attacker locates a public form powered by Sigma Forms Pro, such as a job application page. The attacker submits the form with a PHP payload attached to the file upload field. The plugin accepts the file, writes it to the uploads directory, and returns a path that the attacker can request directly to execute the payload. See the Wordfence Vulnerability Analysis for further technical details.
Detection Methods for CVE-2026-14494
Indicators of Compromise
- New PHP, .phtml, or .phar files appearing under wp-content/uploads/ with recent timestamps
- HTTP POST requests to admin-ajax.php or Sigma Forms Pro submission endpoints containing multipart file payloads from unauthenticated sources
- Outbound connections from the web server to unexpected hosts shortly after form submissions
- WordPress user or option table modifications following anomalous upload events
Detection Strategies
- Inspect web server access logs for POST requests to Sigma Forms Pro endpoints followed by GET requests to newly created files in the uploads directory
- File integrity monitoring on wp-content/uploads/ to flag creation of executable script files
- Alert on WordPress capability changes and unusual unfiltered_upload grants recorded by security plugins
Monitoring Recommendations
- Forward WordPress and web server logs to a centralized analytics platform for correlation of upload activity with subsequent script execution
- Monitor process creation on the web server host for PHP-spawned shells, curl, wget, or reverse shell utilities
- Track EDR telemetry on the underlying host for post-exploitation behavior such as credential access or lateral movement
How to Mitigate CVE-2026-14494
Immediate Actions Required
- Update Sigma Forms Pro to a version later than 1.4.5 as soon as the vendor releases a patched build; consult BDThemes Announcements for release status
- If no fixed version is available, deactivate and remove the Sigma Forms Pro plugin from all affected WordPress sites
- Audit wp-content/uploads/ for unauthorized script files and remove any discovered webshells
- Rotate WordPress administrator credentials, database credentials, and any secrets stored in wp-config.php on compromised sites
Patch Information
At the time of publication, refer to the vendor advisory at BDThemes Announcements for the fixed release covering CVE-2026-14494. Apply the update to every WordPress site running Sigma Forms Pro, including staging and development environments.
Workarounds
- Configure allowed_file_types explicitly on every form to restrict uploads to non-executable types such as pdf, docx, png, and jpg
- Block execution of PHP within the uploads directory using a web server rule, for example a Files directive in Apache or a location block in nginx that denies script handlers
- Place a web application firewall rule in front of the site to block multipart uploads containing PHP tags or executable extensions targeting Sigma Forms Pro endpoints
- Restrict access to affected form pages behind authentication or IP allowlists until a patch is applied
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
