CVE-2026-49765: WordPress Integration for Mailchimp and Contact Form 7, WPForms, Elementor, Ninja Forms plugin <= 1.1.8 - PHP Object Injection vulnerability

Synopsis

PHP Object Injection is a vulnerability where attacker-controlled data is passed to PHP's unserialize() function, allowing the attacker to instantiate arbitrary PHP objects and chain them into code execution or other destructive actions. This affects the WordPress plugin "Integration for Mailchimp and Contact Form 7, WPForms, Elementor, Ninja Forms" at version 1.1.8 and below, and is reachable over the network with no authentication required. Successful exploitation gives an attacker full read, write, and availability impact on the host, which in practice means remote code execution, data theft, or complete site takeover are all on the table. No upstream fix has been published yet; HarborGuard tracks the advisory and will make a patched-image rebuild available the moment one is released.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The vulnerable plugin endpoint is exposed over the network, meaning an attacker can reach and trigger it from the internet without any foothold on the host.

• AuthenticationNot required

  No account or session credential of any kind is needed; the injection point is accessible to anonymous HTTP requests.

• Victim interactionNot required

  The attack is fully server-side and requires no action from any user or site administrator.

• Attack complexityDetail

  Exploit reliability is high and no special environmental conditions, race conditions, or configuration variations are required to trigger the vulnerability.

Blast Radius

• Reads arbitrary files and database contents from the WordPress installation, including stored credentials, API keys, and customer records.
• Writes or modifies files on the server, enabling persistent backdoor placement or defacement of site content.
• Crashes or destabilizes the WordPress application or underlying PHP process, causing service disruption for site visitors.
• Chains deserialized object gadgets into remote code execution, giving the attacker full operating-system-level command execution on the container or host.