CVE-2026-5718: Drag and Drop Multiple File Upload for Contact Form 7 <= 1.3.9.7 - Unauthenticated Arbitrary File Upload via Non-ASCII Filename Blacklist Bypass

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 4.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-17 · updated 2026-06-17
Weakness: CWE-434

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).

Affected products

glenwpcoder Drag and Drop Multiple File Upload for Contact Form 7: through 1.3.9.7

References

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