Unauthenticated Broken Access Control in Newsletters

Executive Summary

CVE-2026-54840 is a Broken Access Control vulnerability in the WordPress Newsletters Plugin versions 4.13 and below.

This vulnerability allows unauthenticated users to perform actions that normally require higher privileges because the plugin is missing proper authorization checks.

It is classified as medium priority with a CVSS score of 7.3 and falls under the OWASP Top 10 category A1: Broken Access Control.

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Impact Analysis

This vulnerability can be exploited by unauthenticated attackers to perform privileged actions on affected websites.

Because there are no authorization checks, attackers could potentially manipulate newsletter functions or other sensitive operations.

The flaw is considered moderately dangerous and could be used in mass campaigns targeting thousands of websites, increasing the risk of widespread exploitation.

Users are strongly advised to update to version 4.14 or seek assistance from hosting providers or developers if updating is not possible.

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Compliance Impact

The vulnerability involves unauthenticated broken access control allowing unauthorized users to perform higher-privileged actions. Such unauthorized access can lead to unauthorized disclosure, modification, or deletion of data, which may impact compliance with data protection regulations like GDPR and HIPAA that require strict access controls to protect personal and sensitive information.

Since the flaw falls under OWASP Top 10's A1: Broken Access Control, it highlights a critical security weakness that can result in data breaches or unauthorized data manipulation, potentially violating regulatory requirements for data confidentiality, integrity, and availability.

Organizations using affected versions of the Newsletters plugin should update immediately to mitigate risks and maintain compliance with relevant standards and regulations.

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Mitigation Strategies

The immediate step to mitigate this vulnerability is to update the WordPress Newsletters Plugin to version 4.14 or later.

If updating is not possible, it is recommended to seek assistance from your hosting provider or a developer.

No virtual patch can be applied due to the nature of the vulnerability.

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