CVE-2026-87796: Multi Uploader for Gravity Forms <= 1.1.9 - Unauthenticated Arbitrary File Upload via Chunked File Upload

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-17 · updated 2026-09-19
Weakness: CWE-434

Description

The Multi Uploader for Gravity Forms plugin for WordPress is vulnerable to Arbitrary File Upload in all versions up to, and including, 1.1.9 via the move_file function. This is due to insufficient file type validation during chunked upload handling. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible.

Affected products

sh1zen Multi Uploader for Gravity Forms: through 1.1.9

References

https://plugins.trac.wordpress.org/browser/gf-multi-uploader/tags/1.1.9/GFMUAddon.class.php#L125
https://plugins.trac.wordpress.org/browser/gf-multi-uploader/tags/1.1.9/inc/GFMUHandlePluploader.class.php#L257
https://plugins.trac.wordpress.org/browser/gf-multi-uploader/tags/1.1.9/inc/GFMU_FileUploader.php#L319
https://plugins.trac.wordpress.org/browser/gf-multi-uploader/tags/1.1.9/inc/GFMU_FileUploader.php#L322
https://plugins.trac.wordpress.org/browser/gf-multi-uploader/tags/1.1.9/inc/GFMU_FileUploader.php#L560
https://www.wordfence.com/threat-intel/vulnerabilities/id/47337bc1-fa3d-470c-9524-859295261017?source=cve

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