MailPoet – Newsletters, Email Marketing, and Automation <= 5.39.0 - Authenticated (Author+) Stored Cross-Site Scripting via Post Title in 'newsletter:post_title' Shortcode
- ID
- WPSEC-2026-0257
- Plugin
- MailPoet – Newsletters, Email Marketing, and Automation (mailpoet)
- Affected
- from 4.44.1 before 5.40.0
- Remediation
- Update to 5.40.0 or later.
- CVSS 3.1
- CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
- Weakness
- CWE-79
- Usage
- Plugin Medium · Affected versions Medium among sites WPSec scans, 2026-10-22
- Attack surface
- MailPoet – Newsletters, Email Marketing, and Automation on WPSec AttackSurface
- Fix released
- Published
Description
The MailPoet plugin for WordPress is vulnerable to Stored Cross-Site Scripting via post titles rendered by the 'newsletter:post_title' shortcode in versions 4.44.1 to 5.39.0. This is due to the plugin stripping HTML tags from the title before decoding HTML entities, so entity-encoded markup in a title is turned into live HTML that is inserted unescaped into the newsletter subject and body. This makes it possible for authenticated attackers, with Author-level access and above, to inject arbitrary web scripts into newsletters and post notifications that use the shortcode, which execute when a user opens the newsletter's 'view in browser' page on the site.
References
- https://wpsec.com/vuln/WPSEC-2026-0257/
- https://plugins.svn.wordpress.org/mailpoet/tags/5.40.0/
- https://wordpress.org/plugins/mailpoet/
Published by WPSec. Provided as is, without warranty. Corrections: contact us.
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