CVE-2026-5718: The Drag and Drop Multiple File Upload for Contact Form 7 plugin for WordPress is vulnerable to arbitrary file upload in versions up to, and including...

Description

The Drag and Drop Multiple File Upload for Contact Form 7 plugin for WordPress is vulnerable to arbitrary file upload in versions up to, and including, 1.3.9.7. This is due to insufficient file type validation that occurs when custom blacklist types are configured, which replaces the default dangerous extension denylist instead of merging with it, and the wpcf7_antiscript_file_name() sanitization function being bypassed for filenames containing non-ASCII characters. This makes it possible for unauthenticated attackers to upload arbitrary files, such as PHP files, to the server, which can be leveraged to achieve remote code execution. The vulnerability was originally reported by Leonid Semenenko (lsemenenko) and partially patched in version 1.3.9.7. A bypass for the patch was separately discovered and reported by Nguyen Hung (Mitchell).

Metrics

CVSS 3.1

8.1/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

4.17%

89.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-434

References

Timeline

Published: Apr 17, 2026
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-5718?

The Drag and Drop Multiple File Upload for Contact Form 7 plugin for WordPress is vulnerable to arbitrary file upload in versions up to, and including, 1.3.9.7. This is due to insufficient file type validation that occurs when custom blacklist types are configured, which replaces the default dangerous extension denylist instead of merging with it, and the wpcf7_antiscript_file_name() sanitization function being bypassed for filenames containing non-ASCII characters. This makes it possible for unauthenticated attackers to upload arbitrary files, such as PHP files, to the server, which can be leveraged to achieve remote code execution. The vulnerability was originally reported by Leonid Semenenko (lsemenenko) and partially patched in version 1.3.9.7. A bypass for the patch was separately discovered and reported by Nguyen Hung (Mitchell).

How severe is CVE-2026-5718?

CVE-2026-5718 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 4.17% probability of exploitation in the next 30 days.

How do I fix CVE-2026-5718?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.