CVE-2026-13439 | Easy Form Builder by WhiteStudio <= 4.0.11 - Unauthenticated Privilege Escalation to Administrator via Password Recovery REST Endpoint

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.

Published: 2026-07-21 Last update: 2026-07-21 Assigner: [email protected] Source: [email protected]
NVD Status：Received，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-13439 is rated Moderate Risk (60.3/100): CVSS Critical severity. Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-13439

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

EPSS has not published a score for this CVE yet—common while NVD analysis or FIRST scoring is still pending. Monitor daily updates and reassess once scores appear.

Common vulnerability scoring system (CVSS) metrics for CVE-2026-13439

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]

Weakness enumeration for CVE-2026-13439

GitHub Security Advisory for CVE-2026-13439

GHSA-3h5m-xwq3-mjmq · Severity: critical — The Easy Form Builder by WhiteStudio plugin for WordPress is vulnerable to Unauthenticated...

Affected software / configurations for CVE-2026-13439

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2026-13439

URL Tags
https://plugins.trac.wordpress.org/browser/easy-form-builder/trunk/includes/class-Emsfb-public.php#L1587
https://plugins.trac.wordpress.org/browser/easy-form-builder/trunk/includes/class-Emsfb-public.php#L5024
https://plugins.trac.wordpress.org/browser/easy-form-builder/trunk/includes/class-Emsfb-public.php#L5060
https://plugins.trac.wordpress.org/browser/easy-form-builder/trunk/includes/class-Emsfb-public.php#L623
https://plugins.trac.wordpress.org/browser/easy-form-builder/trunk/includes/class-Emsfb-public.php#L96
https://plugins.trac.wordpress.org/changeset/3588226/easy-form-builder/trunk/includes/class-Emsfb-public.php
https://plugins.trac.wordpress.org/changeset?old_path=%2Feasy-form-builder/tags/4.0.11&new_path=%2Feasy-form-builder/tags/4.0.12
https://www.wordfence.com/threat-intel/vulnerabilities/id/df8326b6-a443-4f76-a755-49f89af74d7e?source=cve
cvelogic Threat Intelligence