# MP3 Audio Player <= 5.15 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'slider_navigation_vertical_alignment' Shortcode Attribute

- **ID:** WPSEC-2026-1537
- **Plugin:** MP3 Audio Player – Music Player, Podcast Player & Radio by Sonaar (`mp3-music-player-by-sonaar`), https://wordpress.org/plugins/mp3-music-player-by-sonaar/
- **Affected versions:** from 4.6 before 5.16
- **Fixed in:** 5.16 (Update to 5.16 or later.)
- **Severity:** Medium 6.4 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N)
- **Weakness:** CWE-79
- **Usage among sites WPSec scans:** plugin Medium, affected versions Low (as of 2026-10-23)
- **Attack surface analysis:** https://attacksurface.wpsec.com/plugin/mp3-music-player-by-sonaar
- **Fix released:** 2026-10-22
- **Published:** 2026-10-23
- **URL:** https://wpsec.com/vuln/WPSEC-2026-1537/

## Description

The MP3 Audio Player plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'slider_navigation_vertical_alignment' attribute of the plugin's audio player shortcode in all versions up to, and including, 5.15 due to insufficient input sanitization and output escaping when the value is placed into the slider navigation's data-v-align HTML attribute. 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.

## References

- https://wpsec.com/vuln/WPSEC-2026-1537/
- https://plugins.svn.wordpress.org/mp3-music-player-by-sonaar/tags/5.16/
- https://wordpress.org/plugins/mp3-music-player-by-sonaar/

Source: WPSec, https://wpsec.com/vuln/WPSEC-2026-1537/

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.