CVE-2021-4421Network attack vector

Metadata modification via missing nonce validation

Published Jul 12, 2023 · Updated Apr 8, 2026

Cross-site request forgery in Code Supply Co. Advanced Popups 1.1.1 and earlier allows remote attackers to write popup metadata. The metabox_popup_save() handler accepts a forged administrative request without correctly validating a WordPress nonce before saving supplied meta tags. Exploitation requires an unauthenticated attacker to induce a site administrator to perform an action such as following a crafted link, and the documented consequence is unauthorized metadata modification.

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

What happened

Cross-site request forgery in Code Supply Co. Advanced Popups 1.1.1 and earlier allows remote attackers to write popup metadata. The metabox_popup_save() handler accepts a forged administrative request without correctly validating a WordPress nonce before saving supplied meta tags. Exploitation requires an unauthenticated attacker to induce a site administrator to perform an action such as following a crafted link, and the documented consequence is unauthorized metadata modification.

The record

CVE
CVE-2021-4421
Published
Jul 12, 2023
Updated
Apr 8, 2026
Vendor
Code Supply Co.
Product
Advanced Popups
Classifications
CWE-352, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 12, 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

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Is a vulnerable build present?

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

  1. Affected versionversion=0 <=1.1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Code Supply Co. · Advanced Popupsversion=0 <=1.1.1

Published CVSS scores

4.3Wordfence CNACVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
4.0Rapid7AV:N/AC:M/Au:N/C:N/I:P/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

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Your stack

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