Formidable Forms <= 6.28 — Unauthenticated Payment Amount Manipulation via 'item_meta' Parameter
CVE-2026-2888Published · Updated Action summary
Affected: ≤6.28Update to 6.29 or newer
All remediation steps- Severity
- Medium5.3
- CVSS
- 5.3CVSS 3.1 · CNA (Wordfence)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:NWhat does this vector mean?
AV:NAttack vector- Network
AC:LAttack complexity- Low
PR:NPrivileges required- None
UI:NUser interaction- None
S:UScope- Unchanged
C:NConfidentiality- None
I:LIntegrity- Low
A:NAvailability- None
- Required access
- No account needed
- 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≤ 6.28
- Patched in6.29
Update to 6.29 or newer.
You are affected if you run ≤ 6.28. Version 6.29 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.
- No account is needed to exploit this. Treat any exposed site on an affected version as at risk.
What to do
- Update to version 6.29, 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 Michael Iden (Mickhat).
The Formidable Forms plugin for WordPress is vulnerable to an authorization bypass through user-controlled key in all versions up to, and including, 6.28. This is due to the `frm_strp_amount` AJAX handler (`update_intent_ajax`) overwriting the global `$_POST` data with attacker-controlled JSON input and then using those values to recalculate payment amounts via field shortcode resolution in `generate_false_entry()`. The handler relies on a nonce that is publicly exposed in the page's JavaScript (`frm_stripe_vars.nonce`), which provides CSRF protection but not authorization. This makes it possible for unauthenticated attackers to manipulate PaymentIntent amounts before payment completion on forms using dynamic pricing with field shortcodes, effectively paying a reduced amount for goods or services.
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
Timeline
CVE published
Severity medium, CVSS 5.3
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.