CVE-2021-4425Network attack vector

One-time login verification via missing nonce

Published Jul 12, 2023 · Updated Apr 8, 2026

Cross-site request forgery in WPMU DEV Defender Security 2.4.6 and earlier allows remote attackers to verify a one-time login. The verify_otp_login_time() function accepts a forged request without correctly validating a WordPress nonce before marking the login time as verified. An attacker must induce a logged-in site administrator to submit the request, and the resulting integrity impact is limited to the one-time-login verification state.

CVSS severity4.3
Medium
EPSS probability0.56%
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 WPMU DEV Defender Security 2.4.6 and earlier allows remote attackers to verify a one-time login. The verify_otp_login_time() function accepts a forged request without correctly validating a WordPress nonce before marking the login time as verified. An attacker must induce a logged-in site administrator to submit the request, and the resulting integrity impact is limited to the one-time-login verification state.

The record

CVE
CVE-2021-4425
Published
Jul 12, 2023
Updated
Apr 8, 2026
Vendor
WPMU DEV
Product
Defender Security
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 <=2.4.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

WPMU DEV · Defender Securityversion=0 <=2.4.6

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

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Your stack

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