CVE-2026-1303 in MailChimp Campaigns Plugin
Summary
by MITRE • 02/14/2026
The MailChimp Campaigns plugin for WordPress is vulnerable to Missing Authorization in all versions up to, and including, 3.2.4. This is due to missing capability checks on the `mailchimp_campaigns_manager_disconnect_app` function that is hooked to the AJAX action of the same name. This makes it possible for authenticated attackers, with Subscriber-level access and above, to disconnect the site from its MailChimp synchronization app, disrupting automated email campaigns and marketing integrations.
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Analysis
by VulDB Data Team • 02/19/2026
The vulnerability identified as CVE-2026-1303 resides within the MailChimp Campaigns plugin for WordPress, a widely used integration tool that connects WordPress websites with MailChimp's email marketing platform. This plugin enables users to synchronize their WordPress content with MailChimp campaigns, automate email sequences, and manage marketing integrations directly from their WordPress dashboard. The security flaw manifests in the plugin's handling of administrative functions, specifically targeting the disconnect functionality that should require elevated privileges to execute. The vulnerability affects all versions up to and including 3.2.4, representing a significant security gap that has persisted across multiple releases of this popular WordPress plugin.
The technical implementation flaw stems from inadequate capability validation within the `mailchimp_campaigns_manager_disconnect_app` function, which operates as an AJAX handler for the corresponding action. This function lacks proper authorization checks that would normally verify whether the requesting user possesses sufficient privileges to perform the disconnect operation. The absence of these capability checks creates an access control vulnerability that allows authenticated users with Subscriber-level permissions or higher to execute the disconnect function. This represents a clear violation of the principle of least privilege, where users should only be granted access to functions commensurate with their role within the system. The vulnerability maps directly to CWE-863, which addresses "Incorrect Authorization" issues in software systems, where the system fails to properly verify that an actor is authorized to perform a requested operation.
The operational impact of this vulnerability extends beyond simple privilege escalation, creating substantial disruption to marketing and communication workflows for affected WordPress sites. When an authenticated attacker with Subscriber-level access successfully exploits this vulnerability, they can sever the connection between the WordPress site and MailChimp's synchronization service, effectively disabling automated email campaigns, marketing integrations, and content synchronization features. This disruption can result in significant business consequences including loss of automated customer engagement, broken marketing workflows, and potential revenue impact from halted email marketing campaigns. The vulnerability particularly affects organizations that rely heavily on automated email sequences for customer retention, lead nurturing, and content distribution, as the disruption can occur without any visible indication of compromise from the site's administrators.
Organizations affected by this vulnerability should immediately implement mitigations to protect their WordPress installations from exploitation. The primary and most effective mitigation involves updating to the latest version of the MailChimp Campaigns plugin where the authorization checks have been properly implemented. Security teams should also consider implementing additional monitoring and logging around AJAX endpoints, particularly those related to third-party integrations, to detect unauthorized access attempts. Network-level protections such as web application firewalls can provide additional defense-in-depth by blocking suspicious AJAX requests to known vulnerable endpoints. Administrators should review user permissions and ensure that only trusted personnel maintain access to administrative functions, implementing the principle of least privilege more rigorously. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving privilege escalation and defense evasion, as the attacker can leverage existing access to perform unauthorized administrative actions without triggering typical security alerts that would flag more obvious malicious activities.