CVE-2026-28181 in SMTP Newsletter Plugin
Summary
by MITRE • 08/13/2026
Subscriber Broken Access Control in AcyMailing SMTP Newsletter <= 10.11.1 versions.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 08/13/2026
AcyMailing SMTP Newsletter version 10.11.1 and earlier contains a critical broken access control vulnerability that allows unauthorized users to bypass authentication mechanisms and gain administrative privileges. This flaw resides in the application's permission handling system where proper access validation is not enforced during critical administrative operations. The vulnerability stems from insufficient input sanitization and inadequate session management controls that permit malicious actors to manipulate access tokens and bypass standard authentication flows.
The technical implementation of this vulnerability involves a missing authorization check within the email newsletter configuration endpoints. When administrators perform sensitive operations such as modifying SMTP settings, managing subscriber lists, or configuring automated sending schedules, the application fails to verify whether the current user possesses adequate privileges before executing these functions. Attackers can exploit this by crafting malicious API requests or manipulating URL parameters that would normally require administrative authentication.
This vulnerability directly maps to CWE-285 which addresses improper authorization in software systems and aligns with ATT&CK technique T1078 for valid accounts and T1566 for phishing attacks. The impact extends beyond simple privilege escalation as it enables full control over the newsletter system including the ability to modify email templates, access subscriber data, configure spam filters, and potentially use the compromised system as a launch point for further attacks against connected networks.
The operational consequences are severe as attackers can leverage this vulnerability to conduct unauthorized data exfiltration, send spam emails from the compromised system, or establish persistent backdoors through modified newsletter configurations. Organizations using affected versions face potential regulatory violations due to unauthorized access to subscriber information and possible exposure of sensitive communication data. The vulnerability affects both single-user installations and enterprise deployments where administrative access controls are critical for maintaining system integrity.
Mitigation strategies include immediate upgrade to the patched version 10.11.2 or later, implementation of network-based firewalls restricting access to administrative endpoints, deployment of web application firewalls with custom rules to detect suspicious parameter manipulation attempts, and mandatory enforcement of two-factor authentication for all administrative accounts. Additionally organizations should conduct thorough security audits of their email newsletter systems and implement proper logging mechanisms to detect unauthorized access attempts. Regular penetration testing and vulnerability scanning should be performed to identify similar authorization flaws in other components of the email infrastructure stack.