Vulnerability · CVE-2026-84999

The Pie Register Premium plugin for WordPress is vulnerable to Unrestricted File Type Upload in all versions up to, and including, 3.8.4.0 via the piereg_file_upload function.

Q: Which versions are affected?

Compare what you have installed with Pie Register <= 3.8.4. Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

Q: What should an analyst verify?

CWE-434: Unrestricted Upload of File with Dangerous Type. EPSS 0.48%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Published Oct 27, 2026 · catalog updated Oct 29, 2026 · Pie Register Pie Register Premium

Last checked Nov 6, 2026. A connected source was read within the last 7 days.

Patch now

CVE-2026-84999 is in the CISA known-exploited catalog. Confirm Pie Register Pie Register Premium against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Severity: Critical9.8
Known exploitation: CISA KEV and VulnCheck KEV
EPSS: 0.48%
Remediation: Remediation guidance
Affected products: stated Pie Register · vendor Pie Register · vendor Pie Register Pie Register Premium

The Pie Register Premium plugin for WordPress is vulnerable to Unrestricted File Type Upload in all versions up to, and including, 3.8.4.0 via the piereg_file_upload function. This is due to the plugin performing file type validation via wp_check_filetype and wp_check_filetype_and_ext but never checking whether those validation calls produced errors before move_uploaded_file() is called, combined with no nonce or capability check on the AJAX handler. This makes it possible for unauthenticated attackers to upload files of dangerous types (e.g. PHP scripts) that may be executable, which makes remote code execution possible. The server returns the generated destination filename in the response, giving the attacker the exact path needed to trigger the uploaded file.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

stated Pie Register<= 3.8.4
vendor Pie Registerversion unspecified
vendor Pie Register Pie Register Premiumversion unspecified

How to fix CVE-2026-84999

Vendor action
Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Version check
Affected <= 3.8.4
Advisory
Open the cve_org record and follow its fix.
Official advisories

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2026-84999 is in the CISA known-exploited catalog. Confirm Pie Register Pie Register Premium against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Compare what you have installed with Pie Register <= 3.8.4. Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

What should an analyst verify?

CWE-434: Unrestricted Upload of File with Dangerous Type. EPSS 0.48%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

WordPress security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

Oct 27, 2026 · CISA KEV
Known exploited
Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Oct 28, 2026 · EUVD
Detected
The Pie Register Premium plugin for WordPress is vulnerable to Unrestricted File Type Upload in all versions up to, and including, 3.8.4.0 via the piereg_file_upload function. This is due to the plugin performing file type validation via wp_check_filetype and wp_check_filetype_and_ext but never checking whether those validation calls produced errors before move_uploaded_file() is called, combined
Oct 28, 2026 · CVE.org
Updated
The Pie Register Premium plugin for WordPress is vulnerable to Unrestricted File Type Upload in all versions up to, and including, 3.8.4.0 via the piereg_file_upload function. This is due to the plugin performing file type validation via wp_check_filetype and wp_check_filetype_and_ext but never checking whether those validation calls produced errors before move_uploaded_file() is called, combined
Oct 29, 2026 · EUVD
Updated
The Pie Register Premium plugin for WordPress is vulnerable to Unrestricted File Type Upload in all versions up to, and including, 3.8.4.0 via the piereg_file_upload function. This is due to the plugin performing file type validation via wp_check_filetype and wp_check_filetype_and_ext but never checking whether those validation calls produced errors before move_uploaded_file() is called, combined

Sources

CVE.orgVulnerability recordCVE-2026-84999
The Pie Register Premium plugin for WordPress is vulnerable to Unrestricted File Type Upload in all versions up to, and including, 3.8.4.0 via the piereg_file_upload function. This is due to the plugin performing file type validation via wp_check_filetype and wp_check_filetype_an
cve.org
FIRST EPSSExploitation probabilityCVE-2026-84999
30-day exploitation probability 0.48%
first.org
EUVDVulnerability recordEUVD-2026-111559
The Pie Register Premium plugin for WordPress is vulnerable to Unrestricted File Type Upload in all versions up to, and including, 3.8.4.0 via the piereg_file_upload function. This is due to the plugin performing file type validation via wp_check_filetype and wp_check_filetype_an
euvd.enisa.europa.eu
OpenCVEVendor advisoryCVE-2026-84999
CVE-2026-84999 is named on the public OpenCVE page.
opencve.io
VulnCheck KEVConfirmed exploitationCVE-2026-84999
The Pie Register Premium plugin for WordPress is vulnerable to Unrestricted File Type Upload in all versions up to, and including, 3.8.4.0 via the piereg_file_upload function. This is due to the plugin performing file type validation via wp_check_filetype and wp_check_filetype_an
vulncheck.com

References

Freshness

Last verified in this catalog Nov 6, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

VulnCheck KEVOct 31, 2026
EUVDOct 29, 2026
FIRST EPSSOct 28, 2026
CVE.orgOct 28, 2026
OpenCVEOct 28, 2026

Priority score

61/100

Evidence confidence: Very high

CISA lists this vulnerability as known to be exploited.

Confirmed exploitation30/30
EPSS probability1/20
CVSS severity15/15
Public exploit0/10
Internet exposure10/10
Product prevalence5/5
Detection0/5
Threat research0/5

Decision signals

Four separate signals — do not infer one from another.

Critical

CVSS severity
9.8 v3.1
Technical impact. Separate from exploitation likelihood.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS probability
0.48% · p41.52%
Estimated probability of exploitation within 30 days (FIRST).
Known exploitation
Yes · CISA KEV and VulnCheck KEV
CISA KEV since Oct 27, 2026. Ransomware use: Unknown.
Patch availability
Remediation guidance
Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

Stacks

WordPress

Weakness

CWE-434
Unrestricted Upload of File with Dangerous Type
MITRE definition

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