Description
The Newsletter – Send awesome emails from WordPress plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'np1' Custom Field Parameter in all versions up to, and including, 9.4.0 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The subscription endpoint (na=sa) requires no nonce, no capability check, and no CAPTCHA, and the payload can be smuggled past email-address validation by embedding the {profile_1} placeholder in the local part of the submitted address, since WordPress's is_email() permits curly braces there.
References9
- plugins.trac.wordpress.org/browser/newsletter/tags/9.3.9/includ…
- plugins.trac.wordpress.org/browser/newsletter/tags/9.3.9/includ…
- plugins.trac.wordpress.org/browser/newsletter/tags/9.3.9/includ…
- plugins.trac.wordpress.org/browser/newsletter/tags/9.3.9/plugin…
- plugins.trac.wordpress.org/browser/newsletter/tags/9.3.9/profil…
- plugins.trac.wordpress.org/browser/newsletter/tags/9.3.9/subscr…
- plugins.trac.wordpress.org/browser/newsletter/tags/9.3.9/subscr…
- plugins.trac.wordpress.org/changeset?reponame=&old=3711290%40ne…
- www.wordfence.com/threat-intel/vulnerabilities/id/6e61119c-b83e…
Metrics
- CVSS 3.1
-
7.2
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N - EPSS — exploit probability
- 0% percentile: 20 · as of 10 November 2026
- CWE
- CWE-79
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.