CVE-2026-19251 in Ultimate Member Plugin
Summary
by MITRE • 09/02/2026
The Ultimate Member WordPress plugin before 2.13.0 does not check whether a comment has been approved, or whether the profile it belongs to is private, before returning profile activity to unauthenticated visitors, allowing them to read the content of comments still awaiting moderation.
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Analysis
by VulDB Data Team • 09/02/2026
The vulnerability identified in The Ultimate Member WordPress plugin prior to version 2.13.0 represents a significant failure in access control mechanisms within a widely used user management and membership solution for WordPress environments. This flaw specifically affects the handling of profile activity data, which is intended to display recent actions such as comments posted by users on their profiles or other content. The core technical deficiency lies in the backend logic responsible for querying and returning this activity feed. When an unauthenticated visitor requests profile activity information, the application fails to perform two critical security checks before rendering the response. First, it does not verify whether a comment associated with that activity has been approved by a moderator or administrator. Second, it neglects to check if the user profile in question is set to private visibility settings. This combination of oversights allows sensitive data to be exposed to users who should have no access rights whatsoever under normal operational conditions.
From an architectural perspective, this issue stems from improper enforcement of authorization policies on server-side endpoints that serve dynamic content based on user identity and status. In a secure implementation, any request for profile-related metadata must first authenticate the requester's session or permissions level. If the requester is unauthenticated, the system should either return empty data or restrict access entirely unless public visibility has been explicitly configured by the site administrator. The absence of these checks means that the application treats all requests equally regardless of context, effectively bypassing the intended security boundaries established by the plugin’s role-based and profile-visibility configurations. This is a classic example of an insecure direct object reference combined with broken access control, where the system trusts client-side assumptions or fails to validate server-side constraints before processing data retrieval operations.
The operational impact of this vulnerability extends beyond mere privacy violations; it facilitates information disclosure that can aid further attacks against WordPress installations. Unauthenticated attackers can harvest details about pending comments, which may contain personal identifiable information, internal discussions, or sensitive business logic being debated by users who expect their inputs to remain confidential until approved. Furthermore, knowledge of unapproved content can reveal the moderation workflow and potentially expose usernames, email addresses, or other metadata embedded within those draft comments. This level of detail assists threat actors in crafting targeted phishing campaigns, social engineering attacks, or even brute-force attempts against specific user accounts identified through this leaked activity feed. The exposure undermines trust in the platform’s ability to protect member data, which is particularly damaging for sites relying on membership models where privacy expectations are high.
This vulnerability aligns with CWE-284 Improper Access Control and CWE-200 Exposure of Sensitive Information to an Unauthorized Actor as defined by the Common Weakness Enumeration standard. In terms of attack vectors, it corresponds to ATT&CK technique T1530 Data from Cloud Storage Objects or more generally data exfiltration through insecure APIs if viewed in a broader context of web application security. The flaw allows for passive reconnaissance without requiring authentication credentials, placing it within the initial access and discovery phases of an adversary's kill chain. Attackers can automate queries to scrape multiple profiles simultaneously, building comprehensive databases of user activity patterns that would otherwise remain hidden behind login walls or moderation queues.
Mitigation strategies must prioritize immediate patching as well as defensive configuration adjustments. The primary remediation is upgrading the Ultimate Member plugin to version 2.13.0 or later, where these access control checks have been implemented by the developers. Until an upgrade can be performed in production environments, administrators should consider implementing web application firewall rules that restrict access to specific API endpoints associated with profile activity retrieval if those endpoints are known and exposed. Additionally, enforcing strict privacy defaults for new user profiles ensures that even if this vulnerability is exploited, the amount of sensitive data leaked remains minimal. Regular security audits focusing on authorization logic in custom plugins or themes can prevent similar flaws from being introduced during future development cycles. Monitoring server logs for unusual patterns of unauthenticated requests to profile-related endpoints may also help detect exploitation attempts early.