CVE-2026-16062 Overview
CVE-2026-16062 is a PHP object injection vulnerability in the Event Booking Manager for WooCommerce WordPress plugin. Versions before 5.3.7 deserialize user-controlled input in event content fields without adequate validation. Authenticated users with Contributor-level access or higher can inject arbitrary PHP objects into the application. The plugin itself does not ship a Property Oriented Programming (POP) chain. However, a chain present in another installed plugin or theme can escalate the flaw to arbitrary file deletion, sensitive data disclosure, or remote code execution. This issue is an incomplete fix for previously disclosed object-injection advisories in the same plugin [CWE-502].
Critical Impact
Contributor-level attackers can inject PHP objects that, when combined with a gadget chain from another plugin, enable remote code execution on the WordPress host.
Affected Products
- Event Booking Manager for WooCommerce WordPress plugin versions before 5.3.7
- WordPress sites permitting Contributor-level user registration with this plugin installed
- WooCommerce deployments extending event management functionality via this plugin
Discovery Timeline
- 2026-08-02 - CVE-2026-16062 published to NVD
- 2026-08-04 - Last updated in NVD database
Technical Details for CVE-2026-16062
Vulnerability Analysis
The vulnerability stems from insecure deserialization of user-supplied data in event content fields processed by the plugin. When the plugin handles event content submitted by an authenticated Contributor, it passes attacker-controlled strings into PHP's unserialize() function. This allows any serialized object graph in the input to be reconstructed as live PHP objects. The plugin does not contain a directly exploitable POP chain internally. Exploitation therefore requires a gadget chain from another installed plugin, theme, or WordPress core dependency. Once a chain is available, attackers can trigger arbitrary file deletion, read sensitive files such as wp-config.php, or achieve remote code execution. The advisory notes this release is an incomplete remediation of prior object-injection issues, indicating the sanitization or filtering added earlier failed to block all injection paths.
Root Cause
The root cause is the use of unserialize() on data influenced by low-privilege authenticated users without a safe allow-list of expected classes. PHP object injection [CWE-502] enables attackers to instantiate arbitrary classes and trigger magic methods such as __destruct, __wakeup, or __toString during deserialization.
Attack Vector
An attacker authenticates to a WordPress site with a Contributor account or higher. The attacker submits crafted event content containing a serialized PHP payload targeting a known gadget chain in a co-installed plugin. When the plugin processes the field, PHP reconstructs the object and invokes chained methods to reach a sink such as file_put_contents, unlink, or eval.
No verified proof-of-concept code is publicly available. Refer to the WPScan Vulnerability Report for advisory details.
Detection Methods for CVE-2026-16062
Indicators of Compromise
- Event post or booking records containing serialized PHP payloads such as strings beginning with O: or a: followed by class names and property counts.
- Unexpected file creations, deletions, or modifications under wp-content/ shortly after Contributor-level activity.
- Outbound network connections from the PHP worker process to unknown hosts following event content submissions.
Detection Strategies
- Audit the plugin's event content fields for input matching PHP serialization patterns and reject or quarantine matching submissions.
- Enable WordPress audit logging for post creation and metadata updates by users with the Contributor role.
- Correlate PHP-FPM or Apache error logs with __wakeup or __destruct warnings that indicate deserialization of unexpected classes.
Monitoring Recommendations
- Alert on Contributor accounts submitting event posts that contain the substrings O: or C: immediately followed by a numeric length and class name.
- Monitor web server processes for spawning child processes such as sh, bash, or php -r that indicate command execution.
- Track integrity of critical files including wp-config.php, .htaccess, and files in wp-content/uploads/ for unexpected changes.
How to Mitigate CVE-2026-16062
Immediate Actions Required
- Update the Event Booking Manager for WooCommerce plugin to version 5.3.7 or later on all WordPress instances.
- Review existing Contributor and higher user accounts and remove or downgrade any that are not strictly required.
- Inventory all installed plugins and themes to identify components known to contain POP gadget chains and update or remove them.
Patch Information
The vendor addressed the issue in Event Booking Manager for WooCommerce version 5.3.7. Because prior fixes were incomplete, administrators should verify the running version matches or exceeds 5.3.7 rather than relying on earlier hotfixes. See the WPScan Vulnerability Report for advisory tracking.
Workarounds
- Restrict new user registrations and disable self-service Contributor role assignment until the patch is applied.
- Deploy a Web Application Firewall (WAF) rule that blocks POST requests containing PHP serialization signatures in event-related endpoints.
- Temporarily deactivate the plugin on sites where an upgrade cannot be immediately deployed.
# Update the plugin using WP-CLI to remediate CVE-2026-16062
wp plugin update event-booking-manager-for-woocommerce --version=5.3.7
wp plugin get event-booking-manager-for-woocommerce --field=version
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
