# LazyLoad Plugin <= 2.4.0 - Authenticated (Contributor+) Stored Cross-Site Scripting via YouTube Video Title

- **ID:** WPSEC-2026-0539
- **Plugin:** LazyLoad Plugin – Lazy Load Images, Videos, and Iframes (`rocket-lazy-load`), https://wordpress.org/plugins/rocket-lazy-load/
- **Affected versions:** from 2.3.8.2 before 2.4.1
- **Fixed in:** 2.4.1 (Update to 2.4.1 or later.)
- **Severity:** Medium 4.9 (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:N)
- **Weakness:** CWE-79
- **Usage among sites WPSec scans:** plugin Medium, affected versions Medium (as of 2026-10-07)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/rocket-lazy-load
- **Fix released:** 2026-10-06
- **Published:** 2026-10-07
- **URL:** https://wpsec.com/vuln/WPSEC-2026-0539/

## Description

The LazyLoad Plugin plugin for WordPress is vulnerable to DOM-based Stored Cross-Site Scripting via the title of embedded YouTube videos in versions 2.3.8.2 up to, and including, 2.4.0. This is due to the front-end YouTube preview script inserting the video iframe's title, read back from the data-alt attribute, into markup through innerHTML without 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, by embedding a YouTube video whose title they control. Exploitation requires the 'Iframes & Videos' and 'Replace Youtube videos by thumbnail' options to be enabled.

## References

- https://wpsec.com/vuln/WPSEC-2026-0539/
- https://plugins.svn.wordpress.org/rocket-lazy-load/tags/2.4.1/
- https://wordpress.org/plugins/rocket-lazy-load/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-0539/

License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Free to use, share and adapt, also commercially, if you credit WPSec and link to this advisory.