CVE-2026-9676 in F4 Post Tree Plugin
Summary
by MITRE • 06/29/2026
The F4 Post Tree WordPress plugin before 2.0.5 does not perform capability checks or CSRF/nonce verification on one of its AJAX actions, allowing authenticated users with Subscriber-level access and above to modify the parent and menu order of arbitrary posts.
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Analysis
by VulDB Data Team • 06/29/2026
The vulnerability exists within the F4 Post Tree WordPress plugin version 2.0.4 and earlier, where a critical security flaw allows unauthorized modification of post hierarchy through improper access controls. This issue specifically affects the plugin's AJAX handling mechanism which fails to validate user permissions or implement proper cross-site request forgery protection measures. The flaw enables authenticated users possessing Subscriber-level privileges or higher to manipulate the parent-child relationships and menu ordering of any posts within the WordPress installation, regardless of their actual content ownership or editorial permissions.
The technical implementation of this vulnerability stems from the absence of capability checks within the plugin's AJAX endpoint handling code. According to CWE-863, this represents a failure to correctly enforce authorization controls where the system does not properly verify that authenticated users possess the necessary privileges to perform specific actions. The lack of CSRF/nonce verification creates an additional attack surface where malicious actors could potentially exploit this weakness through social engineering or compromised user sessions. This vulnerability operates at the application layer and directly impacts WordPress's content management capabilities, particularly affecting the hierarchical structure and navigation ordering of posts.
The operational impact of this vulnerability extends beyond simple post reordering to potentially disrupt website navigation and content hierarchy in ways that could affect both user experience and search engine optimization. Attackers with Subscriber-level access could manipulate menu structures to redirect users to malicious content or create misleading navigation paths within the site. The vulnerability also presents a risk for privilege escalation scenarios where attackers might use this capability to gain broader control over content management functions. According to ATT&CK framework technique T1078, this represents an authentication bypass or privilege escalation vector that could be leveraged to maintain persistent access through content manipulation.
Mitigation strategies should prioritize immediate plugin updates to version 2.0.5 or later where the capability checks and CSRF protection have been implemented. Administrators should also review user roles and permissions to ensure that only trusted users have Subscriber-level access or higher, particularly in environments where multiple user types exist. Network-based monitoring can help detect unusual post modification patterns that might indicate exploitation attempts. The WordPress security team recommends implementing additional layered defenses such as web application firewalls and regular security audits to prevent similar vulnerabilities from emerging in other plugin components. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates across all WordPress installations.