Description

Subscriber Broken Access Control in AcyMailing SMTP Newsletter <= 10.11.1 versions.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-08-13T14:16:59.800Z",
  "pubdate": "2026-08-13T14:16:59.800Z",
  "executiveSummary": "An access control vulnerability has been identified in the AcyMailing SMTP Newsletter plugin, specifically affecting versions 10.11.1 and prior. This security flaw is classified as a Broken Access Control vulnerability, which arises from insufficient validation of user permissions and authorization checks within the application logic.\nThe vulnerability allows unauthorized actors, specifically subscribers or low-privileged users, to access restricted functionalities or data structures that should be strictly reserved for administrative roles. Successful exploitation of this flaw can lead to unauthorized data exposure, potential modification of newsletter configurations, or execution of privileged actions within the context of the WordPress environment.\nThe risk implications are moderate to high, depending on the specific capabilities exposed through the broken access control boundary. Attackers require a baseline interaction with the system, such as a standard subscriber-level account, to initiate exploitation. No complex cryptographic bypasses are necessary, as the flaw fundamentally relies on missing authorization enforcement checks on sensitive endpoints.\nMitigation requires applying vendor-supplied updates or patches that properly enforce access control lists (ACLs) and capability checks for all administrative functions. Organizations utilizing the affected versions should audit user roles and monitor access logs for anomalous behavior originating from subscriber accounts.",
  "technicalDetails": "The root cause of the vulnerability stems from inadequate server-side authorization enforcement within the AcyMailing SMTP Newsletter plugin for versions <= 10.11.1. When processing requests related to newsletter management, routing, or administrative actions, the application fails to adequately verify whether the authenticated session possesses the requisite capabilities, such as manage_options or specific plugin-defined administrative privileges.\nExploitation of this broken access control vulnerability occurs when an attacker with a low-privileged role, such as a standard subscriber, directly interacts with specific application endpoints or AJAX actions. Because the underlying controller or function lacks proper capability checks (e.g., current_user_can() validation in WordPress), the application processes the incoming request as if it originated from a trusted administrator.\nThe attack flow typically involves the following steps: First, the attacker authenticates as a subscriber to obtain a valid session cookie or nonce, if applicable. Second, the attacker crafts a targeted HTTP request directed toward the vulnerable endpoint or function responsible for administrative operations within AcyMailing. Third, due to the absence of robust access controls, the backend component executes the requested functionality without validating the user's role. Finally, the attacker achieves unauthorized access to restricted features, potentially leading to data leakage or unauthorized modifications.\nThe vulnerable component resides within the access control layer of the plugin, where request routing and permission validation intersect. Network exposure is standard for web applications, as the endpoints are accessible via HTTP/HTTPS protocols wherever the plugin is active. Post-exploitation impact depends on the specific functions exposed via the unvalidated endpoints, potentially allowing attackers to alter mailing lists, view sensitive subscriber data, or interact with SMTP configurations in an unauthorized manner."
}