CVE-2026-4406 Gravity Forms <= 2.9.30 - Reflected Cross-Site Scripting via 'form_ids' Parameter
Unauthenticated attackers can execute arbitrary scripts in victim browsers via a crafted link due to improper output encoding in the Gravity Forms plugin.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-4406?
CVE-2026-4406 is a medium-severity cross-site scripting vulnerability in Gravity Forms, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
The Gravity Forms plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the `form_ids` parameter in the `gform_get_config` AJAX action in all versions up to, and including, 2.9.30. This is due to the `GFCommon::send_json()` method outputting JSON-encoded data wrapped in HTML comment delimiters using `echo` and `wp_die()`, which serves the response with a `Content-Type: text/html` header instead of `application/json`. The `wp_json_encode()` function does not HTML-encode angle brackets within JSON string values, allowing injected HTML/script tags in `form_ids` array values to be parsed and executed by the browser. The required `config_nonce` is generated with `wp_create_nonce('gform_config_ajax')` and is publicly embedded on every page that renders a Gravity Forms form, making it identical for all unauthenticated visitors within the same 12-hour nonce tick. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link. This vulnerability cannot be exploited against users who are authenticated on the target system, but could be used to alter the target page.
Weakness: CWE-79
Which versions are affected by CVE-2026-4406?
How do I fix CVE-2026-4406?
No fix has been published for CVE-2026-4406 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-4406 being exploited?
There is no known exploitation of CVE-2026-4406 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as GHSA-m698-rpjv-64j7.