CVE-2026-12757

Email Subscribers & Newsletters <= 5.9.27 - Unauthenticated Arbitrary Shortcode Execution via Subscriber Name Field

2026-09-07 00:30
Sander Horsman

Strategic Overview

Status
Patched in 5.9.28
Affected Plugin
Email Subscribers & Newsletters – Email Marketing, Post Notifications & Newsletter Plugin for WordPress
Affected Version
<= 5.9.27
CVSS
6.5Medium
Weakness type
CWE-94 · Improper Control of Generation of Code ('Code Injection')
CVE
CVE-2026-12757
View all Email Subscribers & Newsletters – Email Marketing, Post Notifications & Newsletter Plugin for WordPress vulnerabilities

At a glance

CVE-2026-12757 is a medium-severity Improper Control of Generation of Code ('Code Injection') vulnerability in the Email Subscribers & Newsletters WordPress plugin, affecting versions <= 5.9.27. It carries a CVSS score of 6.5 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 5.9.28; sites on affected versions should update now. Disclosed September 2026, reported by Sander Horsman.

Vulnerability Overview

The The Email Subscribers & Newsletters – Email Marketing, Post Notifications & Newsletter Plugin for WordPress plugin for WordPress is vulnerable to arbitrary shortcode execution in all versions up to, and including, 5.9.27. This is due to the software allowing users to execute an action that does not properly validate a value before running do_shortcode. This makes it possible for unauthenticated attackers to execute arbitrary shortcodes.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user.

CWE-94: Improper Control of Generation of Code ('Code Injection')

Reaching this weakness in Email Subscribers & Newsletters <= 5.9.27 takes no account at all. Code injection means input from a request reaches a language construct that evaluates code, so the attacker's text is executed rather than treated as data.

The injected code runs with the web server's privileges, giving the attacker the same access to the database and filesystem as WordPress itself. For Email Subscribers & Newsletters the fix is 5.9.28: builds <= 5.9.27 are affected, anything from 5.9.28 onward is not.

Remediation

Update to version 5.9.28, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: Email Subscribers & Newsletters 5.9.28 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Scanner
  • Login Security

External References

https://www.cve.org/CVERecord?id=CVE-2026-12757https://www.wordfence.com/threat-intel/vulnerabilities/id/6d9b4448-2b63-4704-ac9e-c4db4784638chttps://nvd.nist.gov/vuln/detail/CVE-2026-12757

Related records

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