Formidable Forms <= 6.3 - Authenticated (Subscriber+) Arbitrary Plugin Installation and Activation
Strategic Overview
- Status
- Patched in 6.3.1
- Affected Plugin
- Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More
- Affected Version
< 6.3.1- CVSS
- 6.5Medium
- Weakness type
- CWE-862 · Missing Authorization
- CVE
CVE-2023-2877
At a glance
CVE-2023-2877 is a medium-severity Missing Authorization vulnerability in the Formidable Forms WordPress plugin, affecting versions < 6.3.1. It carries a CVSS score of 6.5 (reachable over the network; low attack complexity; high integrity impact). Exploitation requires an authenticated account at Subscriber level or above. The issue is fixed in version 6.3.1; sites on affected versions should update now. Disclosed May 2023, reported by Alex Sanford.
Vulnerability Overview
The Formidable Forms plugin for WordPress is vulnerable to unauthorized arbitrary plugin installation and activation due to a missing capability check on the screen_page() and can_install_addon_api() functions in versions up to, and including, 6.3. This makes it possible for authenticated attackers, with minimal permissions such as subscribers to retrieve a valid token from the welcome page, and then subsequently install and activate arbitrary plugins onto the site utilizing that key. This can easily be leveraged by attackers to achieve remote code execution as they simply need to install another plugin with a vulnerability or functionality that will aid in further exploitation.
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user. A successful exploit has high impact on integrity.
CWE-862: Missing Authorization
Formidable Forms < 6.3.1 carries this weakness at screen_page(), and reaching it takes an account at Subscriber level or above. A missing authorization check means a function is reachable by anyone who can reach the endpoint, because the code never asks whether the caller is allowed to perform the action.
Any user who can reach the endpoint gets to run an action reserved for higher-privileged roles, from reading protected data to changing settings or content. For Formidable Forms the fix is 6.3.1: builds < 6.3.1 are affected, anything from 6.3.1 onward is not.
Remediation
Update to version 6.3.1, or a newer patched version
How does WordSec protect against this?
Because it turns on account access, WordSec's login security is the relevant layer: role-based two-factor, captcha and brute-force limits raise the cost of getting the account this needs. None of that substitutes for the fix: Formidable Forms 6.3.1 closes this, and updating the plugin is the step that ends it.
- Login Security
- Alerts
External References
Related records
Same weakness class
Other vulnerabilities in Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More
- 9.8CVE-2023-1405: Formidable Forms <= 6.1.2 PHP Object Injection
CVE-2023-1405 - 9.8CVE-2019-15780: Formidable Form Builder <= 4.02 PHP Object Injection
CVE-2019-15780 - 9.6CVE-2021-24884: Formidable Form Builder <= 4.09.04 Stored XSS
CVE-2021-24884 - 9.1Formidable Form Builder <= 2.0.21 Missing Authorization Checks
- 8.8CVE-2014-9309: Formidable Form Builder <= 1.07.11 SQL Injection
CVE-2014-9309 - 8.6Formidable Form Builder < 2.05.03 SQL Injection
- 8.3CVE-2017-20192: Formidable Form Builder < 2.05.03 Stored XSS
CVE-2017-20192 - 7.2CVE-2026-18331: Formidable Forms <= 6.33.1 Stored Cross-Site Scripting
CVE-2026-18331
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