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Vulnerabilities

Vulnerability · CVE-2026-4883

Piotnet piotnet_forms Unrestricted Upload of File with Dangerous Type

Published May 19, 2026 · catalog updated Oct 13, 2026 · Piotnet

Patch now

CVE-2026-4883 is in the CISA known-exploited catalog. Confirm Piotnet 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
0.87%
Remediation
Remediation guidance
Affected products
stated piotnet_forms · vendor Piotnet piotnet_forms

The Piotnet Forms plugin for WordPress is vulnerable to arbitrary file upload due to missing file type validation in the 'piotnetforms_ajax_form_builder' function in all versions up to, and including, 2.1.40. The plugin uses an incomplete extension blacklist that only blocks php, phpt, php5, php7, and exe extensions, while allowing dangerous extensions such as .phar or .phtml to be uploaded. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible. Note: The exploit can only be exploited if a file Initial-access exploit intelligence.

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 piotnet_forms<= 2.1.40
  • vendor Piotnet piotnet_formsversion unspecified

How to fix CVE-2026-4883

What to do

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

Should you patch?

CVE-2026-4883 is in the CISA known-exploited catalog. Confirm Piotnet 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 <= 2.1.40. 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 0.87%. 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.

  1. May 19, 2026 · NIST NVD

    Detected

    The Piotnet Forms plugin for WordPress is vulnerable to arbitrary file upload due to missing file type validation in the 'piotnetforms_ajax_form_builder' function in all versions up to, and including, 2.1.40. The plugin uses an incomplete extension blacklist that only blocks php, phpt, php5, php7, and exe extensions, while allowing dangerous extensions such as .phar or .phtml to be uploaded. This

  2. Jun 17, 2026 · NIST NVD

    Updated

    The Piotnet Forms plugin for WordPress is vulnerable to arbitrary file upload due to missing file type validation in the 'piotnetforms_ajax_form_builder' function in all versions up to, and including, 2.1.40. The plugin uses an incomplete extension blacklist that only blocks php, phpt, php5, php7, and exe extensions, while allowing dangerous extensions such as .phar or .phtml to be uploaded. This

  3. Oct 13, 2026 · CISA KEV

    Known exploited

    Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

  4. Oct 13, 2026 · VulnCheck KEV

    Updated

    The Piotnet Forms plugin for WordPress is vulnerable to arbitrary file upload due to missing file type validation in the 'piotnetforms_ajax_form_builder' function in all versions up to, and including, 2.1.40. The plugin uses an incomplete extension blacklist that only blocks php, phpt, php5, php7, and exe extensions, while allowing dangerous extensions such as .phar or .phtml to be uploaded. This

Sources

  • CVE.orgVulnerability recordCVE-2026-4883

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-4883

    30-day exploitation probability 0.9%

    first.org
  • NIST NVDVulnerability recordCVE-2026-4883

    The Piotnet Forms plugin for WordPress is vulnerable to arbitrary file upload due to missing file type validation in the 'piotnetforms_ajax_form_builder' function in all versions up to, and including, 2.1.40. The plugin uses an incomplete extension blacklist that only blocks php,

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2026-4883

    The Piotnet Forms plugin for WordPress is vulnerable to arbitrary file upload due to missing file type validation in the 'piotnetforms_ajax_form_builder' function in all versions up to, and including, 2.1.40. The plugin uses an incomplete extension blacklist that only blocks php,

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.