CVE-2026-16269

Deferred Deferred - Pending Action

Newsletters Plugin API Authentication Bypass via Type Juggling

Publication date: 2026-08-08

Last updated on: 2026-08-26

Assigner: WPScan

Description

The Newsletters WordPress plugin before 4.16 does not strictly compare its API authentication key, allowing unauthenticated attackers to bypass the API authentication via type juggling and perform privileged actions such as modifying subscriber records and sending emails, when the optional API has been enabled.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-08-08

Last Modified

2026-08-26

Generated

2026-08-28

AI Q&A

2026-08-08

EPSS Evaluated

2026-08-27

NVD

CVE-2026-16269

EUVD

EUVD-2026-54730

Affected Vendors & Products

Vendor	Product	Version / Range
newsletter	newsletters	to 4.16 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-287	When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

Attack-Flow Graph

Executive Summary

The Newsletters WordPress plugin before version 4.16 has a vulnerability where it does not strictly compare its API authentication key. This allows unauthenticated attackers to bypass authentication using type juggling, a technique that exploits loose comparisons in programming. When the optional API is enabled, attackers can perform privileged actions like modifying subscriber records or sending emails without proper authorization.

Detection Guidance

Check the installed version of the Newsletters plugin in WordPress. If it is below 4.16, the system is vulnerable. Use commands like 'wp plugin list' in WordPress CLI or inspect the plugin files directly.

Impact Analysis

If you use the Newsletters plugin version prior to 4.16 with the API enabled, attackers could gain unauthorized access to modify subscriber data or send emails. This could lead to data breaches, spam distribution, or loss of control over your email lists. Users should update to version 4.16 or later to mitigate this risk.

Compliance Impact

This vulnerability could lead to unauthorized access and modification of subscriber data, potentially violating GDPR (data protection) and HIPAA (health information privacy) requirements. Unauthorized access may result in data breaches, triggering mandatory breach notifications and fines under these regulations.

Mitigation Strategies

Update the Newsletters plugin to version 4.16 or later immediately. Disable the optional API feature if not required. Monitor for unauthorized changes to subscriber records or email activity.

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