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 field is added to the form.
CVE-2026-4883
CRITICALNVD 9.89.8—
EchelonGraph scoreHIGH confidence
Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-05-19. NVD baseline CVSS 9.8; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: ghsa, nvd
9.8
- CVSS v3
- 9.8
- EG Score
- 9.8(high)
- EPSS
- 35.1%
- KEV
- Not listed
Published
May 19, 2026
Last Modified
May 19, 2026
References (2)
- security@wordfencehttps://piotnetforms.com
- security@wordfencehttps://www.wordfence.com/threat-intel/vulnerabilities/id/9bd9c9db-d279-4de2-b5e4-ac7d8c919f2a?source=cve
Frequently asked(5)
What is CVE-2026-4883?
CVE-2026-4883 is a critical vulnerability published on May 19, 2026. The Piotnet Forms plugin for WordPress is vulnerable to arbitrary file upload due to missing file type validation in the 'piotnetformsajaxform_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,…
When was CVE-2026-4883 disclosed?
CVE-2026-4883 was first published in the National Vulnerability Database on May 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-4883 actively exploited?
CVE-2026-4883 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 35.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-4883?
CVE-2026-4883 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-4883?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-4883, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-4883
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