CVE-2021-4338Public exploitNetwork attack vector

Authenticated redirect manipulation via missing capability checks

Published Jun 7, 2023 · Updated Apr 8, 2026

Authorization bypass in 404 to 301 3.0.7 and earlier allows remote authenticated users to view, create, and edit redirects. The open_redirect and save_redirect AJAX handlers verify a nonce but omit capability checks, while admin_footer exposes that nonce on backend pages. Any logged-in user can invoke the handlers to install malicious redirects that send visitors to phishing or spam sites.

CVSS severity6.4
Medium
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in 404 to 301 3.0.7 and earlier allows remote authenticated users to view, create, and edit redirects. The open_redirect and save_redirect AJAX handlers verify a nonce but omit capability checks, while admin_footer exposes that nonce on backend pages. Any logged-in user can invoke the handlers to install malicious redirects that send visitors to phishing or spam sites.

The record

CVE
CVE-2021-4338
Published
Jun 7, 2023
Updated
Apr 8, 2026
Vendor
joelcj91
Product
404 to 301 – Redirect, Log and Notify 404 Errors
Classifications
CWE-284, T1566.002
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 7, 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 <=3.0.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

joelcj91 · 404 to 301 – Redirect, Log and Notify 404 Errorsversion=0 <=3.0.7

Published CVSS scores

5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
6.4WordfenceCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-284Improper Access Control
T1566.002Spearphishing Link

Public exploit references

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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