Security readout for executives and security teams
Plain-English summary
CVE-2021-4421 affects the Advanced Popups WordPress plugin through version 1.1.1. A malicious site or link could cause a logged-in administrator to save popup-related meta tags without proper request validation. Business impact is limited integrity risk, but affected sites should update, disable, or remove the plugin if still present.
Executive priority
Treat as routine but time-bound remediation for affected WordPress assets. Prioritize public marketing sites and sites with many administrators because successful exploitation depends on administrator interaction, not direct remote compromise.
Technical view
The issue is CWE-352 cross-site request forgery caused by missing or incorrect nonce validation in metabox_popup_save(). The CVSS v3.1 score is 4.3: network reachable, low complexity, no attacker privileges, user interaction required, with low integrity impact only.
Likely exposure
Exposure is limited to WordPress sites running Advanced Popups version 1.1.1 or earlier. Successful abuse requires a logged-in administrator to interact with a forged request, such as clicking a malicious link.
Exploitation context
The provided sources do not show CISA KEV listing or confirmed active exploitation. The attack is opportunistic and user-driven rather than directly unauthenticated takeover. Evidence supports unauthorized saving of meta tags, not confidentiality loss or availability impact.
Researcher notes
The public record identifies metabox_popup_save() nonce validation as the vulnerable control. The source bundle does not name a specific patched version or provide evidence of exploitation in the wild. Avoid assuming broader impact beyond meta tag modification.
Mitigation direction
- Inventory WordPress sites for the Advanced Popups plugin.
- Update Advanced Popups to a vendor-fixed release; if unavailable, disable or remove it.
- Avoid using affected plugin versions 1.1.1 or earlier.
- Limit administrator browsing while logged in and avoid untrusted links.
- Review vendor and WordPress plugin guidance for the confirmed fixed release.
Validation and detection
- Check each WordPress site for Advanced Popups installation and version.
- Flag any installation at version 1.1.1 or earlier.
- Review popup metadata for unexpected administrator-attributed changes.
- Review WordPress admin activity around suspicious content changes.
- Confirm remediation by verifying the plugin is updated, disabled, or removed.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-352: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-4421 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 4.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N2.81.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.wordfence.com/threat-intel/vulnerabilities/id/dc7b51e5-6eb7-41ba-add3-f083fb34c5e1?source=cveCVE reference
- https://blog.nintechnet.com/25-wordpress-plugins-vulnerable-to-csrf-attacks/CVE reference
- https://blog.nintechnet.com/more-wordpress-plugins-and-themes-vulnerable-to-csrf-attacks/CVE reference
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-3/CVE reference
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-2/CVE reference
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-1/CVE reference
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-5/CVE reference
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-4/CVE reference
- https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=2548724%40advanced-popups&new=2548724%40advanced-popups&sfp_email=&sfph_mail=CVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Cross-Site Request Forgery (CSRF)
Cross-Site Request Forgery (CSRF) represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.