CVE-2026-121874 in Post Duplicator Plugin
Summary
by MITRE • 11/09/2026
The Post Duplicator WordPress plugin before 3.0.18 does not restrict settings saves to its own options, allowing a site administrator on a multisite network who is not a Super Admin to overwrite arbitrary options of their site, including the role definitions, and so grant themselves network-management capabilities.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 11/09/2026
The vulnerability identified in Post Duplicator versions prior to 3.0.18 represents a critical failure in access control mechanisms within WordPress multisite environments. This flaw stems from an insufficient restriction on the saving of plugin settings, which allows any user with administrative privileges for their specific site to modify options that extend beyond the intended scope of the plugin. In a standard single-site installation, this might result in localized configuration changes, but within a multisite network architecture, the implications are significantly more severe due to the hierarchical nature of permissions and the shared infrastructure among multiple sites.
The core technical issue lies in how the plugin handles data persistence for its configuration options. The code fails to validate whether the user initiating the save operation possesses the necessary privileges not just for their individual site, but also for any global or network-wide settings that might be inadvertently exposed through the same interface. This lack of proper authorization checks enables a malicious actor who holds the Administrator role on one subsite to overwrite arbitrary options associated with their installation. Crucially, this includes the ability to modify user role definitions and capabilities assigned to various roles within the WordPress system.
By manipulating these role definitions, an attacker can effectively escalate privileges from a standard site administrator to that of a Super Admin for the entire network. This is achieved by altering the capability arrays associated with existing roles or creating new roles with elevated permissions. Once this modification is persisted in the database, the attacker gains unrestricted access to manage all sites within the multisite network, including the ability to install plugins, update themes, and modify core WordPress files across the entire infrastructure.
The operational impact of this vulnerability is profound, as it compromises the fundamental isolation principle that distinguishes a secure multisite setup from an insecure one. A breach at the subsite level leads directly to full compromise of the network's administrative layer. Attackers can use these elevated privileges to install backdoors, exfiltrate sensitive data from any site in the network, deface websites, or pivot further into internal networks if WordPress is hosted on a compromised server with broader access rights. The ease of exploitation means that even users with minimal malicious intent could inadvertently cause significant damage by misconfiguring settings, while those with hostile intentions can achieve complete control over the digital estate.
Mitigation strategies must prioritize immediate version updates to 3.0.18 or later, where this authorization flaw has been corrected through stricter validation of user capabilities before processing any option saves. For organizations unable to update immediately due to compatibility constraints, manual intervention is required to audit and restrict access to the plugin's settings page for all non-Super Admin users. Additionally, implementing strict file permission controls on wp-config.php and database credentials can limit the potential damage if an attacker gains administrative access. Regular security audits focusing on role management and capability assignments are essential to detect any unauthorized modifications that may have occurred prior to remediation.
This vulnerability aligns with CWE-269, which describes Improper Privilege Management, specifically where a user is granted privileges they should not possess due to flawed logic in the application's access control system. From an offensive security perspective, this scenario maps directly to ATT&CK technique T1078, Valid Accounts, as it involves leveraging legitimate credentials with insufficiently restricted permissions to gain higher-level access. Furthermore, the act of modifying role definitions falls under T1098, Account Manipulation, where attackers alter account properties to maintain persistence or expand their scope of influence within the compromised environment. Understanding these mappings helps security teams better anticipate similar flaws in other plugins and applications that manage user roles and permissions without rigorous validation against network-level authority requirements.