CVE-2026-13439
Received Received - Intake

Unauthenticated Privilege Escalation in Easy Form Builder WordPress Plugin

Publication date: 2026-07-21

Last updated on: 2026-07-21

Assigner: Wordfence

Description
The Easy Form Builder by WhiteStudio plugin for WordPress is vulnerable to Unauthenticated Privilege Escalation to Administrator in versions up to, and including, 4.0.11 This is due to the password recovery flow using the publicly-visible session identifier ('sid') as the password reset token stored in wp_emsfb_temp_links, combined with a publicly-accessible nonce refresh endpoint (Emsfb/v1/nonce/refresh) that issues valid WordPress REST nonces to unauthenticated visitors. This makes it possible for unauthenticated attackers to reset the password of any WordPress user — including administrators — by scraping the public sid from a published login form page, submitting a recovery request for any known user email via Emsfb/v1/forms/message/add, and then calling Emsfb/v1/forms/recovery/efb_set_password with the known sid to set an arbitrary new password and gain full administrator access.

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Meta Information

Published
2026-07-21
Last Modified
2026-07-21
Generated
2026-07-21
AI Q&A
2026-07-21
EPSS Evaluated
N/A
NVD
CVE-2026-13439
EUVD
EUVD-2026-46156

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
whitestudio easy_form_builder to 4.0.11 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-269 The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

Attack-Flow Graph

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Executive Summary

This vulnerability allows unauthenticated attackers to escalate privileges to administrator level in WordPress sites using the Easy Form Builder plugin up to version 4.0.11. Attackers exploit a weak password recovery system that uses a visible session ID as a reset token and a public nonce refresh endpoint to generate valid WordPress REST nonces. By scraping the session ID from a login form page, requesting a password reset for any user, and then setting a new password, attackers gain full administrator access.

Detection Guidance

Check for unauthorized administrator accounts or password reset activities in WordPress. Inspect logs for requests to endpoints like Emsfb/v1/forms/message/add, Emsfb/v1/forms/recovery/efb_set_password, or Emsfb/v1/nonce/refresh. Look for unusual sid values in wp_emsfb_temp_links.

Impact Analysis

If you use the Easy Form Builder plugin on your WordPress site, an attacker could take over your entire website without needing any credentials. They could delete content, install malicious software, steal sensitive data, or deface your site. This could lead to loss of business, reputational damage, and legal consequences depending on the data hosted.

Compliance Impact

This vulnerability could severely impact compliance with GDPR and HIPAA by allowing unauthorized access to personal and sensitive health data. GDPR requires protection of personal data, while HIPAA mandates safeguards for protected health information. A breach could result in regulatory fines, legal action, and mandatory breach notifications to affected individuals.

Mitigation Strategies

Update the Easy Form Builder plugin to the latest version if available. Temporarily disable the plugin if no update is available. Restrict access to WordPress REST API endpoints and review user accounts for unauthorized changes. Monitor for suspicious activity.

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