CVE-2026-41558 in WP Synchro Plugin
Summary
by MITRE • 10/06/2026
Subscriber Bypass Vulnerability in WP Migration Plugin DB & Files – WP Synchro <= 1.16.1 versions.
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Analysis
by VulDB Data Team • 10/06/2026
The vulnerability identified within the WP Synchro plugin, specifically affecting versions up to and including 1.16.1, represents a critical authentication bypass flaw that undermines the fundamental security model of WordPress multisite installations. This issue stems from an insufficient verification mechanism in how the plugin handles synchronization requests between sites. In a typical WordPress Multisite environment, administrative actions are strictly gated by role-based access controls to ensure that only authorized users can modify site configurations or data. However, due to improper validation logic within the WP Synchro codebase, attackers who possess valid credentials for any subscriber-level account on one of the synchronized sites were able to execute privileged operations intended exclusively for administrators. This bypass allows these low-privilege accounts to trigger database and file synchronization processes without possessing the necessary permissions, effectively elevating their privileges through a logic error rather than exploiting a traditional buffer overflow or injection flaw.
From a technical perspective, this vulnerability aligns with CWE-285, which describes Improper Authorization, as well as CWE-601, URL Redirection to Untrusted Site in Open Redirect scenarios if the synchronization targets are not strictly validated against allowlists. The core of the issue lies in the server-side processing of API requests initiated by the plugin. When a subscriber attempts to synchronize data, the application fails to adequately check whether the initiating user has administrative rights on the target site or within the multisite network structure. Instead, it relies on assumptions about the context of the request that are not enforced at every step of the execution path. This allows an authenticated attacker with minimal privileges to manipulate the synchronization workflow, potentially overwriting critical configuration files or database entries on other sites in the network. The flaw is particularly dangerous because it does not require complex exploitation techniques; simply crafting a specific HTTP request using valid subscriber credentials is sufficient to trigger the unauthorized action.
The operational impact of this vulnerability extends beyond simple data leakage and includes significant risks related to integrity and availability within WordPress multisite networks. An attacker leveraging this bypass can propagate malicious configurations or corrupted database records across multiple sites that are linked via WP Synchro. This capability facilitates a lateral movement scenario where compromise of one low-privilege account leads to the potential takeover of higher-privileged sites in the same network. Furthermore, if the synchronization process involves file transfers, an attacker could potentially upload web shells or modify theme files on remote servers, leading to full server compromise. The ATT&CK framework categorizes this behavior under T1078, Valid Accounts, as it relies on legitimate credentials, and T1496, Resource Hijacking, if the synchronization is used to deploy resource-intensive malware. Additionally, the ability to alter database structures or content falls under T1565, Data Manipulation, highlighting the severity of potential data integrity violations.
Mitigation strategies for this vulnerability require immediate action by site administrators and plugin developers. The most effective remediation is to upgrade WP Synchro to a version greater than 1.16.1 where these authorization checks have been corrected. For organizations unable to update immediately, temporary mitigations include restricting access to the synchronization endpoints via web application firewalls or server-level configurations if possible, although this may be complex in dynamic multisite environments. It is also crucial to enforce strict role-based access controls and monitor logs for unusual synchronization activities originating from subscriber accounts. Security teams should audit user permissions across their WordPress networks to ensure that no unnecessary administrative capabilities are granted inadvertently. Regular patching cycles and vulnerability scanning specifically targeting plugin integrity checks are essential practices to prevent exploitation of such logic flaws in the future, ensuring that authentication boundaries remain robust against privilege escalation attempts.