Formidable Forms <= 6.3 — Authenticated (Subscriber+) Arbitrary Plugin Installation and Activation
CVE-2023-2877Published · Updated Action summary
Affected: <6.3.1Update to 6.3.1 or newer
All remediation steps- Severity
- Medium6.5
- CVSS
- 6.5CVSS 3.1 · CNA (Wordfence)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:NWhat does this vector mean?
AV:NAttack vector- Network
AC:LAttack complexity- Low
PR:LPrivileges required- Low
UI:NUser interaction- None
S:UScope- Unchanged
C:NConfidentiality- None
I:HIntegrity- High
A:NAvailability- None
- Weakness
- CWE-862 Missing Authorization
- Required access
- Unknown
- Exploit prediction (EPSS)
- No score
- CISA KEV
- Not listed
On this page8
Am I affected?
Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder formidable
- Affected< 6.3.1
- Patched in6.3.1
Update to 6.3.1 or newer.
You are affected if you run < 6.3.1. Version 6.3.1 and later are not affected by this issue.
- Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder.
- No admin access? Run a passive check of your site. It reads public files only.
What to do
- Update to version 6.3.1, or a newer patched version
- Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
- Watch Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder to get an email when the next vulnerability is published.
Advisory
Source description from Wordfence Intelligence, credited to Alex Sanford.
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.
Exploits & references
Proof-of-concept & detection
No public proof-of-concept or detection template is known for this vulnerability.
Advisories & patches
- Advisorywordfence.com
Related CVEs
More in Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder
All 29| Severity | Vulnerability | CVE | Published |
|---|---|---|---|
| High8.8 | Authenticated (Subscriber+) Arbitrary Plugin Installation via 'file_url' Parameter ≤6.35Update to 7.0 | CVE-2026-89435 | |
| High7.5 | Unauthenticated Denial of Service <7.0Update to 7.0 | CVE-2026-85642 | |
| Medium5.3 | Unauthenticated Content Injection ≤6.34Update to 6.35 | CVE-2026-85641 | |
| Medium6.5 | Unauthenticated Arbitrary Shortcode Execution ≤6.34Update to 6.35 | CVE-2026-19857 | |
| High7.2 | Unauthenticated Stored Cross-Site Scripting via 'frm_user_id' Parameter ≤6.33.1Update to 6.34 | CVE-2026-18331 |
- High8.8Authenticated (Subscriber+) Arbitrary Plugin Installation via 'file_url' Parameter
≤6.35Update to 7.0
- High7.5Unauthenticated Denial of Service
<7.0Update to 7.0
- Medium5.3Unauthenticated Content Injection
≤6.34Update to 6.35
- Medium6.5Unauthenticated Arbitrary Shortcode Execution
≤6.34Update to 6.35
- High7.2Unauthenticated Stored Cross-Site Scripting via 'frm_user_id' Parameter
≤6.33.1Update to 6.34
Same weakness (Missing Authorization)
All Missing Authorization| Severity | Vulnerability | CVE | Published |
|---|---|---|---|
| High7.2 | Unauthenticated Stored Cross-Site Scripting via Comment User-Agent Header | CVE-2026-120688 | |
| Critical9.8 | Unauthenticated Arbitrary File Upload via File Upload via Public Form Submission | CVE-2026-125055 | |
| Critical9.8 | Unauthenticated PHP Object Injection to Remote Code Execution via 'form' Parameter | CVE-2026-119077 | |
| Medium5.3 | Unauthenticated Sensitive Information Exposure in 'search' Parameter | CVE-2026-121518 |
- High7.2Unauthenticated Stored Cross-Site Scripting via Comment User-Agent Header
EZ SQL Reports Shortcode Widget and DB Backup
≤5.25.25Update to 5.26.45
- Critical9.8Unauthenticated Arbitrary File Upload via File Upload via Public Form Submission
Chatterbug Forms – Fast, Flexible WordPress Form Builder
≤1.0.2Update to 1.1
- Critical9.8Unauthenticated PHP Object Injection to Remote Code Execution via 'form' Parameter
ELEX WordPress HelpDesk & Customer Ticketing System
≤3.3.9Update to 3.4.0
- Medium5.3Unauthenticated Sensitive Information Exposure in 'search' Parameter
Customer Reviews for WooCommerce
≤5.127.0Update to 5.128.0
Timeline
CVE published
Severity medium, CVSS 6.5
Record last updated
Sources & licenses
Wordfence record- Vulnerability data
- Wordfence Intelligence. Copyright 2012-2026 Defiant Inc. Licensed under the CC BY-SA 4.0.
- CVE® identifiers
- Copyright 1999-2026 The MITRE Corporation. Used under the CVE Program. CVE® is a registered trademark of The MITRE Corporation.
- CVSS / CWE
- National Vulnerability Database (NVD), shown unmodified. This product uses the NVD API but is not endorsed or certified by the NVD.
- VulnCrest content
- Summary, remediation guidance and page layout © VulnCrest. Not sourced from NVD.