CVE-2026-105886 in Ultimate Post Kit Plugin
Summary
by MITRE • 10/08/2026
Missing Authorization vulnerability in BdThemes Ultimate Post Kit ultimate-post-kit allows Exploiting Incorrectly Configured Access Control Security Levels.This issue affects Ultimate Post Kit: from n/a through 4.5.5.
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Analysis
by VulDB Data Team • 10/08/2026
The identified security flaw within the BdThemes Ultimate Post Kit plugin, specifically affecting versions up to and including 4.5.5, represents a critical failure in access control mechanisms known as Missing Function Level Access Control or Broken Access Control. This vulnerability stems from an incorrect configuration of security levels that governs how users interact with specific administrative functions or data resources within the WordPress environment. In a properly secured system, every request to perform an action must be validated against the user's current permissions and role capabilities before execution occurs. However, in this instance, the application fails to adequately verify whether the initiating user possesses the necessary privileges for the requested operation, thereby allowing unauthorized entities to bypass intended restrictions.
From a technical perspective, this flaw typically manifests when endpoints or AJAX handlers associated with the plugin do not enforce strict capability checks using standard WordPress functions such as current_user_can() or similar authorization logic tailored to custom post types and meta data managed by Ultimate Post Kit. An attacker who has authenticated access at even the lowest privilege level, such as a subscriber or contributor role, can potentially manipulate HTTP requests to execute administrative tasks intended solely for editors or administrators. This could include modifying site configurations, accessing sensitive user data, altering published content without approval workflows, or executing arbitrary code if combined with other input validation weaknesses. The core issue lies in the assumption that client-side restrictions are sufficient security boundaries, ignoring the reality that these can be easily bypassed using standard web request manipulation tools.
The operational impact of this vulnerability is significant for any website relying on Ultimate Post Kit to manage complex post structures or custom content types. Successful exploitation allows attackers to escalate their privileges within the application context, effectively gaining control over aspects of the site they should not have access to. This can lead to defacement, data exfiltration, or further compromise through the installation of malicious plugins or backdoors via administrative interfaces that were inadvertently exposed due to the missing authorization checks. For organizations handling sensitive information or maintaining public-facing services, this breach undermines trust and compliance with security standards requiring strict separation of duties and role-based access control.
This vulnerability aligns closely with CWE-269, which describes Improper Privilege Management, where a user is granted privileges that exceed their assigned role. Furthermore, it maps to the MITRE ATT&CK framework under T1078, specifically Valid Accounts, as attackers leverage legitimate but insufficiently restricted credentials to move laterally or escalate access within the system environment. The lack of server-side validation for function-level permissions creates a direct pathway for unauthorized actions that compromise the integrity and confidentiality of the web application ecosystem.
To mitigate this risk, immediate action is required by updating Ultimate Post Kit to version 4.5.6 or any subsequent release where these authorization checks have been rigorously implemented and tested. Site administrators should verify their plugin versions regularly through automated scanning tools integrated into their CI/CD pipelines or security monitoring dashboards. In the interim, before an update can be applied, it is advisable to restrict access to the WordPress admin area using IP whitelisting if feasible, although this does not fully remediate the underlying code flaw since authenticated attackers from allowed IPs could still exploit the issue. Additionally, implementing a Web Application Firewall with rules targeting common exploitation patterns for broken access control may provide an additional layer of defense by blocking suspicious request structures associated with privilege escalation attempts. Regular security audits and penetration testing focusing on role-based access controls are recommended to ensure that similar gaps do not exist in other custom or third-party components integrated into the platform.