CVE-2026-103999
HighCVSS 7.2Summary
The Ultra Addons for Contact Form 7 plugin for WordPress (versions up to and including 3.5.54) is vulnerable to stored Cross-Site Scripting via File Upload due to insufficient input sanitization and output escaping. An unauthenticated attacker can inject arbitrary web scripts into pages that execute when a user accesses the injected page.
Risk Assessment
Bypassing the extension blocklist by uploading text-type files with HTML content can lead to malicious code execution in the user's browser.
Recommendation
Update the Ultra Addons for Contact Form 7 plugin to a version later than 3.5.54 or disable it; consider tightening file upload rules.
Other vulnerabilities in Ultra Addons for Contact Form 7
See all- CVE-2026-82901Critical
The Ultra Addons for Contact Form 7 plugin for WordPress is vulnerable to Arbitrary File Upload due to insufficient file type validation in the 'uacf7_wpcf7_mail_components' function in all versions up to, and including, 3.5.50. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible. Note: This is only exploitable when the plugin's PDF Generator module is enabled, which is disabled by default.
- CVE-2026-84750Medium
The Ultra Addons for Contact Form 7 WordPress plugin before 3.5.51 does not validate the type or extension of files uploaded through one of its form fields, and stores them at a predictable public path with the attacker-chosen extension intact, allowing unauthenticated users to upload arbitrary files. The PHP handler shipped by default with the Debian and Ubuntu Apache packages maps .phar to PHP alongside .php and .phtml, so on that stack the uploaded file is executed and the issue leads to Remote Code Execution and full site takeover. Where the host routes only .php to the PHP handler, the same file is instead served from the site's own origin with its script intact, leading to Stored Cross-Site Scripting.
- CVE-2026-12801Medium
The Ultra Addons for Contact Form 7 plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the Range Slider 'data-label' and 'data-separator' attributes in all versions up to, and including, 3.5.43 due to insufficient input sanitization and output escaping. This allows authenticated attackers with contributor-level access and above to inject arbitrary web scripts.
Original NVD description (English source)
The Ultra Addons for Contact Form 7 plugin for WordPress is vulnerable to Stored Cross-Site Scripting via File Upload in all versions up to, and including, 3.5.54 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The extension blocklist gatekeeper is bypassed by uploading text-type files (.txt, .csv, .vtt, .srt, .asc) whose contents begin with an HTML payload such as '<BODY onload=…>', as the check classifies these files as text/plain without inspecting their byte content.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS