CVE-2026-9656 in HubSpot All-In-One Marketing Plugin
Summary
by MITRE • 07/17/2026
The HubSpot All-In-One Marketing – Forms, Popups, Live Chat plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 11.3.62 via the wp_localize_script() / window.leadinConfig JavaScript object. This makes it possible for authenticated attackers, with contributor-level access and above, to extract the site's plaintext HubSpot OAuth refresh token exposed via the window.leadinConfig JavaScript object, which can then be used to access or modify data in the connected HubSpot tenant. Although the refresh token is stored at rest with AES-256-CTR encryption, decryption occurs server-side before the plaintext value is passed to wp_localize_script(), rendering the at-rest encryption ineffective against this exposure path.
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Analysis
by VulDB Data Team • 07/17/2026
The vulnerability identified in the HubSpot All-In-One Marketing plugin represents a critical sensitive information exposure flaw that undermines the security posture of WordPress installations. This issue affects all versions up to and including 11.3.62, where the plugin improperly exposes authentication credentials through client-side JavaScript objects. The vulnerability specifically targets the wp_localize_script() function which is commonly used to pass server-side data to client-side JavaScript environments. When this function is employed to serialize configuration data containing OAuth refresh tokens, it creates an unintended information disclosure channel that can be exploited by malicious actors with appropriate privileges.
The technical flaw manifests through the window.leadinConfig JavaScript object which contains plaintext HubSpot OAuth refresh tokens in its serialized output. This occurs because despite the refresh token being stored at rest using AES-256-CTR encryption, the decryption process happens server-side before the token is passed to the wp_localize_script() function. The vulnerability classification aligns with CWE-201, which addresses the exposure of sensitive information through improper data handling in web applications. The flaw essentially nullifies the effectiveness of at-rest encryption measures since the plaintext credentials are made accessible to any JavaScript running in the browser context.
Authenticated attackers with contributor-level access or higher can exploit this vulnerability to extract the plaintext refresh token and subsequently gain unauthorized access to the connected HubSpot tenant. This creates a significant operational impact as it allows adversaries to perform data access and modification operations within the HubSpot environment without requiring additional authentication factors. The attack vector is particularly concerning because it leverages legitimate WordPress user permissions, making detection more challenging in security monitoring systems. The compromised credentials can be used to read, modify, or delete marketing data, contact information, and other sensitive business assets stored within the HubSpot platform.
This vulnerability demonstrates a fundamental flaw in how authentication tokens are handled in web applications, particularly when transitioning between server-side and client-side execution environments. The exposure through wp_localize_script() represents a common pattern that has been documented in various security advisories, highlighting the need for proper input validation and output sanitization of data passed to JavaScript contexts. Organizations should implement immediate mitigations including plugin updates to versions that address this information disclosure, review of user permissions to limit contributor access where possible, and enhanced monitoring for unusual JavaScript behavior in WordPress installations. The incident underscores the importance of following security best practices such as the principle of least privilege and proper credential handling as outlined in industry standards like NIST SP 800-53 and ISO/IEC 27001 frameworks.