A vulnerability in the separate Ninja Forms – File Upload add-on was exploited against WordPress sites, according to Wordfence. It is not a flaw in the base Ninja Forms plugin itself. If your site uses the add-on, check its version and update it to the latest vendor-supported release; Wordfence identified version 3.3.27 as the complete fix in April 2026, while version 3.3.25 was only a partial fix.
What the Ninja Forms vulnerability did
The flaw, tracked as CVE-2026-0740, affected Ninja Forms – File Upload versions through 3.3.26, according to Wordfence’s April 6, 2026 disclosure. On a site exposing a Ninja Forms form with a file-upload field, an unauthenticated attacker could exploit the upload handler to place an arbitrary file on the server. The handler checked the uploaded file’s source name but did not adequately validate the destination filename’s type or extension; insufficient filename sanitization also left a path-traversal route. An attacker could potentially upload a PHP file and execute it, leading to site compromise.
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The GitHub Advisory Database record assigns the vulnerability a CVSS 3.1 score of 9.8, rated Critical. That score reflects the advisory’s assessment of severity and attack conditions—not the number of sites successfully compromised.
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Wordfence says versions up to and including 3.3.26 were affected. Version 3.3.25, released February 10, 2026, was a partial patch; version 3.3.27, released March 19, was identified as the full fix. Because the cited reports do not establish the latest release as of October 7, 2026, install the add-on’s current vendor-supported version and confirm its release number in current vendor or plugin information. Do not rely on 3.3.25 as a complete fix.
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The File Upload component is a separate add-on. Updating only the base Ninja Forms plugin does not necessarily update it. Check the add-on itself and its installed version.
How to check and protect a WordPress site
- Check whether the add-on is installed. In the WordPress dashboard, review the installed plugins for Ninja Forms – File Upload. Determine its version; do not infer the add-on’s status from the base Ninja Forms plugin version.
- Update the add-on. Install the latest vendor-supported release. The complete fix named in Wordfence’s April 2026 report was 3.3.27, but verify whether a later supported release is now available.
- Review possible exposure. If the site ran an affected version before updating, inspect the webroot and
/wp-content/uploadsfor unexpected PHP files. Review access logs for requests to/wp-admin/admin-ajax.php?action=nf_fu_upload. These are investigation leads, not proof of compromise by themselves. - Investigate suspicious findings. If you find unfamiliar executable files or other signs of unauthorized access, preserve relevant logs and follow an established incident-response process to investigate and clean the site. Avoid treating deletion of one file as proof that the site is safe.
A firewall can provide an additional defensive layer, but it is not a replacement for installing the patch. Wordfence’s threat report explicitly urged affected site owners to patch even if a firewall rule was in place.
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What is known about exploitation
Wordfence said it began receiving and validating the vulnerability report on January 8, 2026, and deployed firewall protection for its Premium, Care, and Response customers. The vendor acknowledged the report on January 12; a patch was sent for review on January 27. The partial release followed on February 10, and the full fix on March 19. Wordfence publicly disclosed the flaw on April 6 and reported attacks starting that same day.
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1Fix the driver behind crashes, sound loss and screen glitches2Repair Windows errors before they cause bigger problems3Scan for outdated or missing drivers - takes under a minuteIn an April 16, 2026 report, Wordfence said its firewall had blocked more than 118,600 exploit attempts. That is Wordfence’s cumulative blocked-attempt count as of the report—not a count of confirmed successful attacks or a global total. Wordfence also described the add-on as having an estimated 50,000 active installations; that estimate does not indicate how many were vulnerable or compromised.
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