CVE-2025-9260: Fluent Forms WordPress Plugin RCE Vulnerability

CVE-2025-9260 Overview

CVE-2025-9260 affects the Fluent Forms plugin for WordPress, a widely deployed contact form and survey builder. The vulnerability is a PHP Object Injection flaw ([CWE-502]) rooted in the parseUserProperties function, which deserializes untrusted input. Authenticated attackers with Subscriber-level access or higher can inject arbitrary PHP objects. When combined with a Property-Oriented Programming (POP) chain present in the plugin, attackers can read arbitrary files on the server. If the PHP configuration option allow_url_include is enabled, the flaw escalates to remote code execution.

Critical Impact
Subscriber-level users can trigger deserialization of untrusted input to read arbitrary files, with remote code execution possible when allow_url_include is enabled.

Affected Products

Fluent Forms plugin for WordPress versions 5.1.16 through 6.1.1
Version 6.1.0 attempted patch, but introduced a fatal error due to a missing class import
Version 6.1.2 is considered the fully patched release

Discovery Timeline

2025-09-03 - CVE-2025-9260 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-9260

Vulnerability Analysis

The vulnerability resides in the parseUserProperties function within the Fluent Forms plugin. The function passes attacker-controllable input to PHP's unserialize() routine without validation. Any authenticated WordPress user, including low-privileged Subscribers, can supply a crafted serialized payload. PHP then reconstructs objects from that payload and invokes magic methods such as __wakeup, __destruct, or __toString on the resulting instances.

The plugin ships with classes that can be chained into a POP gadget. The identified chain traverses through the View component under vendor/wpfluent/framework/src/WPFluent/View/View.php, which enables attackers to read arbitrary files accessible to the web server user. When the PHP directive allow_url_include is enabled, the same primitive expands to including remote files, resulting in remote code execution.

Root Cause

The root cause is unsafe deserialization of user-supplied input inside parseUserProperties. The function calls unserialize() on data that originates from HTTP request parameters processed by the shortcode parser. WordPress plugins that rely on unserialize() for user-controlled data are consistently vulnerable to object injection when exploitable classes exist in the runtime.

Attack Vector

Exploitation requires an authenticated session at Subscriber level or higher, which is a low bar on WordPress sites that allow open registration. The attacker submits a serialized PHP object through a form field or endpoint that reaches EditorShortcodeParser::parseUserProperties. The plugin deserializes the payload, instantiating the crafted object graph and executing the POP chain through the View class to read files such as wp-config.php. See the WordPress FluentForm Editor Shortcode Parser source and the WordPress FluentForm View Component for the vulnerable code paths.

No verified public exploit code is available. The vulnerability mechanism is documented in the Wordfence Vulnerability Report.

Detection Methods for CVE-2025-9260

Indicators of Compromise

HTTP POST requests to Fluent Forms submission endpoints containing serialized PHP payloads beginning with O: or a: in form field values
Unexpected reads of sensitive files such as wp-config.php, /etc/passwd, or plugin secrets by the web server process
Web server error logs referencing EditorShortcodeParser.php or class instantiation failures from the plugin's View component
New administrative WordPress accounts or unexpected changes to user roles following form submissions from low-privileged accounts

Detection Strategies

Inspect Fluent Forms request bodies for serialized object signatures such as O: followed by a class name and length, which indicate object injection attempts
Monitor PHP error and access logs for stack traces originating in wpfluent/framework/src/WPFluent/View/View.php triggered by form submissions
Correlate Subscriber-level authentication events with subsequent access to sensitive files or outbound HTTP requests from the web server

Monitoring Recommendations

Enable WordPress audit logging to track user role changes, plugin installations, and configuration modifications by low-privileged accounts
Alert on any PHP process reading wp-config.php or configuration files outside the standard WordPress bootstrap sequence
Track outbound network connections from PHP-FPM or Apache workers to identify RCE follow-on activity when allow_url_include is misconfigured

How to Mitigate CVE-2025-9260

Immediate Actions Required

Upgrade the Fluent Forms plugin to version 6.1.2 or later on all WordPress sites
Audit WordPress user accounts and disable open registration if it is not required for site functionality
Verify that the PHP directive allow_url_include is disabled in php.ini to eliminate the remote code execution path
Rotate WordPress secrets stored in wp-config.php if arbitrary file read exploitation is suspected

Patch Information

The vendor released an initial fix in version 6.1.0, but the patch introduced a fatal error caused by a missing class import. Version 6.1.2 is considered the fully corrected release and should be deployed. Administrators running any version between 5.1.16 and 6.1.1 remain vulnerable.

Workarounds

Restrict access to the vulnerable Fluent Forms endpoints using a Web Application Firewall (WAF) rule that blocks serialized PHP payloads in request parameters
Disable the Fluent Forms plugin until the upgrade to 6.1.2 can be completed
Set allow_url_include=Off and allow_url_fopen=Off in php.ini to prevent escalation from file read to remote code execution

bash

# Configuration example: verify PHP hardening on WordPress hosts
php -r "echo 'allow_url_include=' . ini_get('allow_url_include') . PHP_EOL;"
php -r "echo 'allow_url_fopen=' . ini_get('allow_url_fopen') . PHP_EOL;"

# Update Fluent Forms via WP-CLI
wp plugin update fluentform --version=6.1.2