CVE-2026-49104: Keap Integration PHP Object Injection

CVE-2026-49104 Overview

CVE-2026-49104 is an unauthenticated PHP Object Injection vulnerability in the WordPress plugin Integration for Keap/Infusionsoft and Contact Form 7, WPForms, Elementor, Formidable, Ninja Forms. The flaw affects plugin versions <= 1.2.1 and stems from insecure deserialization of untrusted input [CWE-502]. Remote attackers can exploit the vulnerability over the network without authentication or user interaction. Successful exploitation can lead to arbitrary code execution, data tampering, and full compromise of the WordPress site.

Critical Impact
Unauthenticated attackers can inject crafted PHP objects to trigger property-oriented programming chains, potentially achieving remote code execution on affected WordPress installations.

Affected Products

Integration for Keap/Infusionsoft and Contact Form 7 WordPress plugin (versions <= 1.2.1)
Integration for Keap/Infusionsoft and WPForms, Elementor WordPress plugin (versions <= 1.2.1)
Integration for Keap/Infusionsoft and Formidable, Ninja Forms WordPress plugin (versions <= 1.2.1)

Discovery Timeline

2026-06-15 - CVE-2026-49104 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2026-49104

Vulnerability Analysis

The vulnerability is classified as Insecure Deserialization [CWE-502], commonly referred to as PHP Object Injection. The plugin passes attacker-controlled input to PHP's unserialize() function without validating the source or content of the serialized data. When unserialize() processes attacker-controlled bytes, PHP instantiates arbitrary class objects defined in the application or its dependencies.

Attackers leverage existing classes that implement magic methods such as __wakeup(), __destruct(), or __toString() to build property-oriented programming (POP) chains. These chains can trigger file writes, file reads, SQL execution, or arbitrary code execution depending on the gadgets available in the WordPress core, plugins, or themes loaded at runtime.

The attack requires no authentication and no user interaction. The network-accessible attack surface combined with the unauthenticated entry point makes mass exploitation feasible against exposed WordPress installations.

Root Cause

The root cause is the unsafe deserialization of untrusted input within the plugin's request handling logic. The plugin treats incoming serialized data as trusted and forwards it directly to PHP's native deserialization routines. No type whitelisting, signature verification, or input validation is applied before the data reaches unserialize().

Attack Vector

The attack vector is network-based. An attacker submits a crafted HTTP request containing a serialized PHP payload to a publicly reachable plugin endpoint. The payload encodes a POP chain that executes when the resulting object is destroyed or referenced. See the Patchstack Vulnerability Advisory for endpoint-specific technical details.

Detection Methods for CVE-2026-49104

Indicators of Compromise

HTTP POST or GET requests containing serialized PHP payloads such as strings beginning with O:, a:, or s: followed by class names and property counts.
New or modified PHP files in the wp-content/uploads/ or plugin directories that were not deployed by administrators.
Outbound network connections from the web server process to unfamiliar hosts following requests to plugin endpoints.
WordPress administrator accounts created without a corresponding audit log entry.

Detection Strategies

Inspect web server access logs for request parameters containing serialized PHP patterns targeting plugin routes associated with cf7-infusionsoft.
Deploy a Web Application Firewall (WAF) rule that flags request bodies matching PHP serialization grammar on plugin endpoints.
Compare plugin file integrity against a known-good baseline to identify unauthorized modifications.

Monitoring Recommendations

Monitor the WordPress installation for unexpected child processes spawned by PHP-FPM or the web server user.
Alert on the creation of new PHP files within writable WordPress directories.
Track outbound DNS and HTTP traffic from web servers hosting the affected plugin.

How to Mitigate CVE-2026-49104

Immediate Actions Required

Update the affected plugin to a version higher than 1.2.1 as soon as the vendor publishes a patched release.
Disable and remove the plugin if a patched version is not yet available and the functionality is not business-critical.
Restrict access to plugin endpoints at the WAF or reverse proxy layer until patching is complete.
Audit the WordPress installation for indicators of compromise including unauthorized administrator accounts and modified PHP files.

Patch Information

Consult the Patchstack Vulnerability Advisory for the latest patch availability and fixed version information. At the time of publication, the vulnerability affects all versions up to and including 1.2.1.

Workarounds

Block requests containing serialized PHP signatures (O:, a:, s:) to plugin endpoints using WAF rules.
Apply the principle of least privilege to the web server user to limit the blast radius of code execution.
Enable PHP's disable_functions directive to restrict dangerous functions such as exec, system, and passthru where operationally feasible.

bash

# Example WAF rule pattern (ModSecurity) to block PHP serialization payloads
SecRule ARGS "@rx (?:^|[&=])O:[0-9]+:\"[A-Za-z_\\\\]+\":[0-9]+:\{" \
    "id:1049104,phase:2,deny,status:403,msg:'PHP Object Injection attempt CVE-2026-49104'"