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CriticalVulnerabilityCVE-2026-84999updated 28 Oct 2026, 06:24 UTC

Pie Register Premium WordPress plugin lets anyone upload dangerous files

Anyone on the internet, even without logging in, can upload files such as PHP scripts to the website. If the server runs those files, an attacker can take control of the site.

Official, 2 sources
SeverityCriticalCVSS 9.8 of 10
Being exploited?UnclearNo reports either way yet
Fix available?UnclearNo fixed version published in the sources yet
How sure is this?Official, 2 sourcesBacked by an official source

How the attack works simplified

  1. 1AttackerNo login or account needed
  2. 2Upload requestSends PHP file to AJAX handler
  3. 3Plugin accepts fileType check errors are ignored
  4. 4File saved to serverResponse reveals exact filename
  5. 5Script executedAttacker requests the uploaded file
  6. ResultAttacker runs code on the server

What happened

The piereg_file_upload AJAX handler in Pie Register Premium for WordPress validates file types but never checks whether validation failed before calling move_uploaded_file(), and it has no nonce or capability check. The response also reveals the destination filename.

Why it is dangerous: An unauthenticated attacker can upload executable files and run them, leading to remote code execution, site takeover, data theft, or malware hosting. Any site running the plugin with a server that executes uploaded PHP is at risk.

Are you affected?

You are affected if you run the Pie Register Premium plugin version 3.8.4.0 or earlier on your WordPress site.

Pie Register Premium (WordPress plugin), all versions up to and including 3.8.4.0

What to do

  1. Check your installed Pie Register Premium version and treat 3.8.4.0 or earlier as vulnerable.
  2. Update to a fixed version as soon as the vendor releases one; check the plugin's update page or the GitHub advisory for the patched release.
  3. If no patch is available yet, deactivate the plugin or block access to the piereg_file_upload AJAX action.
  4. Review your uploads folder for unexpected PHP or other executable files and remove any you do not recognize.

Timeline

  1. 28 Oct 2026, 03:17 UTC
    Publicly disclosed
  2. 28 Oct 2026, 03:17 UTC
    Reported by NVD · NVD
  3. 28 Oct 2026, 03:22 UTC
    Picked up by Zero Radar
  4. 28 Oct 2026, 06:24 UTC
    GitHub Advisory reported on it · GitHub Advisory

Sources 2 reports, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-84999 · GHSA-356m-cxhj-j59p
CVSS
9.8 / 10
EPSS
0.5% chance of exploitation within 30 days
Disclosed
28 Oct 2026, 03:17 UTC
On Zero Radar
28 Oct 2026, 03:22 UTC (5 min after disclosure)
Last change
28 Oct 2026, 06:24 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

Pie Register Premium WordPress plugin lets anyone upload dangerous files · Zero Radar