CVE-2021-4405 | ElasticPress <= 3.5.3 - Cross-Site Request Forgery Bypass

The ElasticPress plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 3.5.3. This is due to missing or incorrect nonce validation on the epio_send_autosuggest_allowed() function. This makes it possible for unauthenticated attackers to send allowed parameters for autosuggest to elasticpress[.]io 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-2021-4405 is rated Low Risk (30.1/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.16%). 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-2021-4405

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 2026-03-26 0.13% 0.16% +0.03%
2 2025-11-21 0.16% 0.13% -0.03%
3 2025-11-18 — 0.16% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-4405

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-2021-4405

Affected software / configurations for CVE-2021-4405

Vendor Product Version Raw CPE
10up elasticpress <= 3.5.3 cpe:2.3:a:10up:elasticpress:*:*:*:*:*:wordpress:*:*

References for CVE-2021-4405

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/ Third Party Advisory
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/ Not Applicable
https://plugins.trac.wordpress.org/changeset/2473455/elasticpress/trunk/includes/classes/Feature/Autosuggest/Autosuggest.php Patch
https://www.wordfence.com/threat-intel/vulnerabilities/id/8ab8eb9d-1427-4e99-8986-179147e0862e?source=cve Third Party Advisory
cvelogic Threat Intelligence