Gravity Forms Plugin up to 3.1.2 on WordPress Post Custom Field create_post deserialization

Summaryinfo

A vulnerability classified as critical was found in Gravity Forms Plugin up to 3.1.2. This issue affects the function GFFormsModel::create_post of the component Post Custom Field. Such manipulation leads to deserialization. This vulnerability is referenced as CVE-2026-103039. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Gravity Forms Plugin up to 3.1.2. Affected by this issue is the function GFFormsModel::create_post of the component Post Custom Field. The manipulation with an unknown input leads to a deserialization vulnerability. Using CWE to declare the problem leads to CWE-502. The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at wordfence.com. This vulnerability is handled as CVE-2026-103039 since 09/30/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 10/30/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• WordPress Plugin

Name

• Gravity Forms Plugin

Version

• 3.1.0
• 3.1.1
• 3.1.2

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CPE 2.2info

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