# CVE-2026-12939: Tribulant Newsletters Lite Stored XSS in post_thumbnail shortcode

Source: https://junglewise.ai/threats/cve-2026-12939-tribulant-newsletters-lite-stored-xss-in-post-thumbnail-shortcode  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-29. Updated: 2026-07-29  
License: CC BY 4.0 with a link back

CVE-2026-12939 · Severity: medium · CVSS 6.4 · Published 2026-07-29

The Newsletters Lite plugin for WordPress, which is used to manage email marketing and newsletters, contains a security flaw that allows users with contributor-level access or higher to inject malicious scripts into website pages. These scripts will automatically run in the browser of any visitor who views the affected page. This could lead to unauthorized actions being performed on behalf of site administrators or the theft of sensitive session information.

Vendors: [Tribulant](https://junglewise.ai/threats/vendors/tribulant).

## Quick answers

**Is CVE-2026-12939 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-12939 being exploited in the wild.

**How severe is CVE-2026-12939?** Medium severity, with a CVSS score of 6.4, published 29 July 2026.

**Which products and versions are affected?** Tribulant Newsletters Lite up to and including 4.15.

**Is there a fix for CVE-2026-12939?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-12939 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-12939?** Check whether you run Tribulant Newsletters Lite at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The Newsletters Lite plugin for WordPress is vulnerable to Stored Cross-Site Scripting (XSS) due to insufficient input sanitization and output escaping in the post_thumbnail() method within helpers/shortcode.php. Specifically, the user-controlled '$link' shortcode attribute is concatenated directly into an HTML href attribute without being processed by functions like esc_url() or esc_attr(). This allows authenticated attackers with contributor-level permissions or higher to inject arbitrary web scripts into pages. These scripts execute in the context of a user's browser whenever they visit the compromised page. The vulnerability affects all versions up to and including 4.15.

## Affected products

- Tribulant Newsletters Lite up to and including 4.15

## Timeline

- 2026-07-29: disclosed: NVD publication date

## References

- [https://plugins.trac.wordpress.org/browser/newsletters-lite/tags/4.15/helpers/shortcode.php](https://plugins.trac.wordpress.org/browser/newsletters-lite/tags/4.15/helpers/shortcode.php)
- [https://plugins.trac.wordpress.org/browser/newsletters-lite/tags/4.15/helpers/shortcode.php](https://plugins.trac.wordpress.org/browser/newsletters-lite/tags/4.15/helpers/shortcode.php)
- [https://plugins.trac.wordpress.org/browser/newsletters-lite/tags/4.15/helpers/shortcode.php](https://plugins.trac.wordpress.org/browser/newsletters-lite/tags/4.15/helpers/shortcode.php)
- [https://plugins.trac.wordpress.org/browser/newsletters-lite/tags/4.15/includes/checkinit.php](https://plugins.trac.wordpress.org/browser/newsletters-lite/tags/4.15/includes/checkinit.php)
- [https://plugins.trac.wordpress.org/changeset?reponame=&old=3621582%40newsletters-lite&new=3621582%40newsletters-lite](https://plugins.trac.wordpress.org/changeset?reponame=&old=3621582%40newsletters-lite&new=3621582%40newsletters-lite)
- [https://www.wordfence.com/threat-intel/vulnerabilities/id/2ca8ab94-45b8-4705-b23b-dbc743572121?source=cve](https://www.wordfence.com/threat-intel/vulnerabilities/id/2ca8ab94-45b8-4705-b23b-dbc743572121?source=cve)

## Related threats

- [Tribulant Newsletters Lite Stored XSS in newsletters_post shortcode](https://junglewise.ai/threats/cve-2026-12938-tribulant-newsletters-lite-stored-xss-in-newsletters-post)