CVE-2021-24427Public exploitNetwork attack vector

Stored XSS via unescaped CDN settings

Published Jul 12, 2021 · Updated Aug 3, 2024

Stored XSS in W3 Total Cache before 2.1.3 allows remote authenticated users with administrator access to execute scripts in visitors' browsers. The CDN settings handler stores crafted cdn_cnames values without sufficient sanitization and later emits them into generated pages without output escaping. Exposure requires a multisite installation or disabled unfiltered_html handling, and script execution occurs when a visitor loads an injected page.

CVSS severity4.8
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

Stored XSS in W3 Total Cache before 2.1.3 allows remote authenticated users with administrator access to execute scripts in visitors' browsers. The CDN settings handler stores crafted cdn_cnames values without sufficient sanitization and later emits them into generated pages without output escaping. Exposure requires a multisite installation or disabled unfiltered_html handling, and script execution occurs when a visitor loads an injected page.

The record

CVE
CVE-2021-24427
Published
Jul 12, 2021
Updated
Aug 3, 2024
Vendor
Web Ventures
Product
W3 Total Cache
Classifications
CWE-79, T1190
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jul 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.1.3 <2.1.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Web Ventures · W3 Total Cacheversion=2.1.3 <2.1.3

Published CVSS scores

3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
4.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:R/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1190Exploit Public-Facing Application

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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