CVE-2021-4405Network attack vector

Autosuggest configuration change via missing nonce validation

Published Jul 1, 2023 · Updated Apr 8, 2026

Cross-site request forgery in 10up ElasticPress 3.5.3 and earlier allows remote attackers to send allowed autosuggest parameters to ElasticPress.io. The epio_send_autosuggest_allowed() handler processes the request without correctly validating the ep_epio_nonce value before forwarding the parameters. Exploitation requires an administrator to follow a crafted link or perform an equivalent attacker-induced action, and the resulting impact is limited to modifying the autosuggest configuration sent to the service.

CVSS severity4.3
Medium
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Cross-site request forgery in 10up ElasticPress 3.5.3 and earlier allows remote attackers to send allowed autosuggest parameters to ElasticPress.io. The epio_send_autosuggest_allowed() handler processes the request without correctly validating the ep_epio_nonce value before forwarding the parameters. Exploitation requires an administrator to follow a crafted link or perform an equivalent attacker-induced action, and the resulting impact is limited to modifying the autosuggest configuration sent to the service.

The record

CVE
CVE-2021-4405
Published
Jul 1, 2023
Updated
Apr 8, 2026
Vendor
10up
Product
ElasticPress
Classifications
CWE-352, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 1, 2023CVE publishedPublication date reported by the CVE source.
  2. Apr 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=3.5.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

10up · ElasticPressversion=0 <=3.5.3

Published CVSS scores

4.3WordfenceCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-352Cross-Site Request Forgery (CSRF)
T1204.001User Execution: Malicious Link

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo