CVE-2026-49105: WP Zendesk Auth Bypass Vulnerability

CVE-2026-49105 Overview

CVE-2026-49105 is an unauthenticated PHP Object Injection vulnerability affecting the WordPress plugin WP Zendesk for Contact Form 7, WPForms, Elementor, Formidable and Ninja Forms in versions <= 1.1.4. The flaw is classified under [CWE-502] Deserialization of Untrusted Data. Remote attackers can exploit the issue over the network without authentication or user interaction. Successful exploitation can lead to arbitrary object instantiation, which may chain to remote code execution, file deletion, or data exfiltration when a suitable POP (Property-Oriented Programming) gadget chain is present in the WordPress installation.

Critical Impact
Unauthenticated attackers can inject crafted serialized PHP objects to compromise confidentiality, integrity, and availability of affected WordPress sites.

Affected Products

WP Zendesk for Contact Form 7, WPForms, Elementor, Formidable and Ninja Forms (plugin slug cf7-zendesk)
All plugin versions up to and including 1.1.4
WordPress sites with the plugin installed and active

Discovery Timeline

2026-06-15 - CVE-2026-49105 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2026-49105

Vulnerability Analysis

The plugin passes attacker-controlled input to a PHP deserialization routine such as unserialize() without validating the data source or restricting allowed classes. When PHP deserializes the payload, it instantiates objects and triggers magic methods such as __wakeup(), __destruct(), or __toString(). Attackers chain these magic methods through gadget classes available in WordPress core, other active plugins, or the bundled Composer dependencies.

The attack does not require authentication or user interaction. Network reachability to the vulnerable HTTP endpoint is sufficient. The impact scales with the gadget chains available on the target site, ranging from arbitrary file write to full remote code execution.

Root Cause

The root cause is unsafe deserialization of untrusted input. The plugin invokes PHP object deserialization on a parameter that an unauthenticated user can control. No allowlist, signature verification, or type check is performed before the data reaches the deserialization sink.

Attack Vector

An attacker sends an HTTP request containing a serialized PHP payload to a plugin endpoint that processes Zendesk form integration data. The serialized blob references gadget classes whose magic methods perform sensitive operations when the object is destroyed or coerced to a string. The Patchstack advisory linked under references documents the affected entry point.

No verified public exploit or proof-of-concept code is available at the time of writing. For technical details, see the Patchstack Vulnerability Report.

Detection Methods for CVE-2026-49105

Indicators of Compromise

HTTP POST or GET requests containing PHP serialized markers such as O:, a:, or s: directed at cf7-zendesk plugin endpoints
Unexpected PHP processes spawning shell utilities (sh, bash, curl, wget) from the www-data or PHP-FPM user context
New or modified PHP files under wp-content/uploads/ or plugin directories with recent timestamps
Outbound connections from the WordPress host to unknown infrastructure shortly after plugin endpoint requests

Detection Strategies

Inspect web server access logs for requests targeting cf7-zendesk plugin paths that include serialized object signatures in query strings or POST bodies
Deploy WAF rules that flag serialized PHP object patterns (O:\d+:\") in inbound HTTP traffic to WordPress sites
Compare installed plugin versions against the patched release and alert on any host running <= 1.1.4

Monitoring Recommendations

Enable PHP error logging and review entries referencing unserialize(), __wakeup, or __destruct failures
Monitor file integrity on wp-content/plugins/, wp-content/uploads/, and core PHP files for unexpected changes
Correlate WordPress authentication logs with administrative actions following anomalous requests to the plugin

How to Mitigate CVE-2026-49105

Immediate Actions Required

Update the WP Zendesk plugin to a version above 1.1.4 as soon as the vendor publishes a fixed release
If no patched version is available, deactivate and remove the plugin from all affected WordPress sites
Audit the WordPress installation for indicators of compromise, including unauthorized admin accounts, modified theme or plugin files, and unknown scheduled tasks (wp_cron)
Rotate WordPress secret keys in wp-config.php and reset administrator credentials if compromise is suspected

Patch Information

Review the Patchstack Vulnerability Report for the latest fix status. No fixed version is referenced in the NVD record at publication time. Apply the vendor patch as soon as it becomes available.

Workarounds

Restrict access to the WordPress site behind a WAF that blocks serialized PHP payloads in HTTP request bodies and query strings
Apply virtual patching rules from Patchstack, Wordfence, or equivalent providers to block exploitation of the vulnerable endpoint
Limit network access to the WordPress administrative and plugin endpoints to trusted IP ranges where feasible
Disable the plugin until a fixed version is installed if the Zendesk integration is not business-critical

bash

# Disable the vulnerable plugin via WP-CLI
wp plugin deactivate cf7-zendesk
wp plugin delete cf7-zendesk

# Verify the plugin is no longer present
wp plugin list --status=active | grep -i zendesk