Security readout for executives and security teams
Plain-English summary
This is a WordPress plugin issue in Custom Banners. A malicious site or link could cause a logged-in administrator to unknowingly submit a forged request that changes plugin custom fields. The business risk is limited integrity impact, but exposed WordPress sites should still remove or update affected versions because administrator interaction is the main barrier.
Executive priority
Handle in normal vulnerability remediation cycles, faster for public or business-critical WordPress sites. This is not shown as actively exploited, but it affects admin-mediated content integrity and is usually straightforward to inventory and remediate.
Technical view
CVE-2021-4407 is a CWE-352 cross-site request forgery issue in Custom Banners through version 3.2.2. The reported cause is missing or incorrect nonce validation in saveCustomFields(). The CVSS 3.1 score is 4.3, with network reachability, no privileges required, user interaction required, and low integrity impact.
Likely exposure
Exposure is limited to WordPress sites running the Custom Banners plugin in versions up to and including 3.2.2. Sites without this plugin, or with versions confirmed outside the affected range, are not indicated as exposed by the supplied sources.
Exploitation context
The supplied sources do not show CISA KEV listing or active exploitation. Exploitation requires social engineering a logged-in site administrator into taking an action, such as following a malicious link, while authenticated to WordPress.
Researcher notes
The key technical point is nonce validation failure around saveCustomFields(). Keep validation limited to version review, code review, and authorized test environments. Evidence supports CSRF impact to custom field changes, but the prompt bundle does not provide safe exploit details or confirmed exploitation telemetry.
Mitigation direction
- Inventory WordPress sites for the Custom Banners plugin and installed version.
- Update Custom Banners according to WordPress plugin or vendor guidance.
- Remove or disable the plugin where it is unused or cannot be updated.
- Limit administrator sessions and reinforce anti-phishing controls for WordPress admins.
- Review plugin changelog or WordPress Trac notes before closing remediation.
Validation and detection
- Confirm whether Custom Banners is installed on each WordPress site.
- Record the installed plugin version and compare it with the affected range.
- Review saveCustomFields() for nonce validation in the deployed plugin code.
- Check WordPress admin audit logs for unexpected custom field changes.
- Verify remediation by confirming the plugin is updated, removed, or disabled.
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-2021-4407 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/8f4c086d-8209-4212-9d91-67238c1a9143?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=2473385%40custom-banners&new=2473385%40custom-banners&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.