CVE-2026-126537

Ninja Forms - File Uploads <= 3.3.36 - Unauthenticated Arbitrary File Deletion via 'files[].data.file_path' Parameter via 'extra.saveProgress'

2026-11-11 00:01
daroo

Strategic Overview

Status
Patched in 3.3.37
Affected Plugin
Ninja Forms - File Uploads
Affected Version
<= 3.3.36
CVSS
9.1Critical
Weakness type
CWE-22 · Improper Limitation of a Pathname to a Restricted Directory
CVE
CVE-2026-126537
View all Ninja Forms - File Uploads vulnerabilities

At a glance

CVE-2026-126537 is a critical-severity Improper Limitation of a Pathname to a Restricted Directory vulnerability in the Ninja Forms - File Uploads WordPress plugin, affecting versions <= 3.3.36. It carries a CVSS score of 9.1 (reachable over the network; low attack complexity; high integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 3.3.37; sites on affected versions should update now. Disclosed November 2026, reported by daroo.

Vulnerability Overview

The Ninja Forms - File Uploads add-on for WordPress is vulnerable to Arbitrary File Deletion (and arbitrary file read via S3/Dropbox/Google Drive exfiltration) in versions up to, and including, 3.3.36. The flaw spans NF_FU_Fields_Upload::process() in includes/fields/upload.php — which returns early (leaving the client-supplied files[] intact) whenever a public submission carries a nonempty extra.saveProgress — and NF_FU_External_Abstracts_Service::process_upload() in includes/external/abstracts/service.php, whose authoritative-path reload only fires when the client sends upload_id. By omitting upload_id, an attacker's data[file_path] survives into the Background Upload queue and is used by both upload_file_to_s3() (as SourceFile) and the maybe_delete_server_file() unlink() call in includes/external/abstracts/backgroundupload.php, with no canonicalization or upload-directory containment check (the plugin's own is_path_within_upload_dir() helper is only applied on admin paths). This makes it possible for unauthenticated attackers to delete arbitrary files on the affected site's server which may make remote code execution possible — specifically, deleting wp-config.php forces WordPress into its setup screen, enabling full site takeover.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on integrity, availability.

CWE-22: Improper Limitation of a Pathname to a Restricted Directory

Ninja Forms - File Uploads <= 3.3.36 carries this weakness at process(), and reaching it takes no account at all. Path traversal happens when user-controlled text is used to build a filesystem path without being constrained to an intended directory, so sequences like ../ walk the resolved path somewhere else.

Depending on the operation, it means reading files outside the intended folder — wp-config.php being the usual target — or writing to and deleting paths the web server can touch. For Ninja Forms - File Uploads the fix is 3.3.37: builds <= 3.3.36 are affected, anything from 3.3.37 onward is not.

Remediation

Update to version 3.3.37, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Ninja Forms - File Uploads 3.3.37 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Login Security
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-126537https://www.wordfence.com/threat-intel/vulnerabilities/id/3670e2aa-6d8e-4ba5-ab65-49bd2a3dcacchttps://nvd.nist.gov/vuln/detail/CVE-2026-126537

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C