CVE-2026-89097 in Ad Inserter Plugin
Summary
by MITRE • 10/13/2026
The Ad Inserter – Ad Manager & AdSense Ads plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 2.8.18 via the ai_wp_footer_hook. This makes it possible for authenticated attackers, with subscriber-level access and above, to extract sensitive data including the server's internal IP address, PHP configuration, WordPress and theme versions, hardening constants, the plugin's full block matrix, and all post meta values including underscore-prefixed protected keys such as API tokens and private integration state written by other plugins.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability identified in Ad Inserter – Ad Manager & AdSense Ads for WordPress represents a critical failure in access control logic within the plugin's footer hook implementation, specifically affecting versions up to 2.8.18. This flaw allows authenticated users with subscriber-level privileges or higher to trigger an information disclosure mechanism that exposes sensitive server and application data. The root cause lies in the improper handling of user capabilities during the execution of the ai_wp_footer_hook function, which fails to enforce strict permission checks before rendering diagnostic or configuration-related content into the page footer. This misconfiguration effectively bypasses the intended security boundaries established by WordPress's role-based access control system, allowing low-privilege accounts to interact with administrative-level data structures without authorization.
From a technical perspective, the exploitation of this vulnerability does not require complex injection techniques but rather relies on the attacker simply visiting any page or post where the plugin is active and enabled. Upon loading such pages, the vulnerable hook executes code that outputs detailed system information directly into the HTML source of the response. This includes internal server IP addresses which can facilitate further network reconnaissance, PHP configuration details that reveal potential misconfigurations in the hosting environment, and specific version numbers for WordPress and the active theme. These version identifiers are particularly dangerous as they allow attackers to cross-reference known vulnerabilities associated with those exact software versions, significantly narrowing the attack surface for subsequent exploitation attempts.
The impact of this information exposure extends beyond simple reconnaissance, posing a severe risk to application integrity and data confidentiality. The vulnerability exposes hardening constants that may indicate whether security measures such as debug mode or file editing restrictions are active or disabled in the wp-config.php file. Furthermore, it reveals the plugin's full block matrix configuration, providing attackers with insight into how ads are structured and inserted, which can aid in crafting targeted attacks against ad-serving mechanisms. Most critically, the flaw results in the leakage of all post meta values, including those prefixed with underscores that are conventionally treated as private or protected by WordPress standards. This includes API tokens, authentication keys, and private integration states written by other plugins, effectively compromising third-party service integrations and potentially leading to account takeovers or unauthorized data access across multiple services linked through these exposed credentials.
This vulnerability aligns closely with CWE-200: Information Exposure, as it involves the unintentional disclosure of sensitive information that aids an attacker in further exploitation. In terms of the MITRE ATT&CK framework for enterprise environments, this behavior corresponds to T1592: Gather Victim Host Information and T1589: Gather Victim Identity Information, where adversaries collect details about the target environment to plan subsequent attacks. The exposure of API tokens also touches upon CWE-798: Use of Hard-coded Credentials if those tokens are static, or more broadly CWE-359: Exposure of Private Personal Information depending on the nature of the meta data exposed.
Mitigation strategies must prioritize immediate patching and access control review. Administrators should upgrade Ad Inserter to version 2.8.19 or later where this issue has been addressed by implementing stricter capability checks within the ai_wp_footer_hook function. Until an update is applied, it is advisable to restrict user roles that can edit posts and pages to administrators only if feasible, thereby limiting exposure to users with higher privilege levels who are less likely to be compromised via phishing or credential stuffing attacks. Additionally, organizations should audit their WordPress installations for other plugins that may expose similar meta data through footer hooks or AJAX endpoints. Implementing a Web Application Firewall (WAF) can also provide an additional layer of defense by detecting and blocking requests that attempt to exploit known information disclosure patterns in common plugin structures. Regular security audits focusing on the principle of least privilege are essential to prevent low-privilege accounts from accessing administrative-level data through misconfigured plugins or themes.