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

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.

Published: 2023-07-01 Last update: 2026-04-08 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-4404 is rated Low Risk (30.6/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.17%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-4404

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-27 0.12% 0.17% +0.06%
2 2025-11-21 0.16% 0.12% -0.05%
3 2025-11-18 — 0.16% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-4404

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 1.4 [email protected]

Weakness enumeration for CVE-2021-4404

Affected software / configurations for CVE-2021-4404

Vendor Product Version Raw CPE
eventespresso event_espresso_4_decaf <= 4.10.11 cpe:2.3:a:eventespresso:event_espresso_4_decaf:*:*:*:*:*:wordpress:*:*

References for CVE-2021-4404

URL Tags
https://blog.nintechnet.com/25-wordpress-plugins-vulnerable-to-csrf-attacks/ Not Applicable
https://blog.nintechnet.com/more-wordpress-plugins-and-themes-vulnerable-to-csrf-attacks/ Not Applicable
https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-1/ Not Applicable
https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-2/ Not Applicable
https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-3/ Not Applicable
https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-4/ Not Applicable
https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-5/ Third Party Advisory
https://plugins.trac.wordpress.org/changeset/2554360/event-espresso-decaf/trunk/core/domain/services/pue/Stats.php Patch
https://www.wordfence.com/threat-intel/vulnerabilities/id/89d3a9da-2496-4f75-ad8f-65629f198fe5?source=cve Third Party Advisory
cvelogic Threat Intelligence