CVE-2026-78438Network attack vector

Stored XSS via nested background-style rewriting

Published Sep 5, 2026 · Updated Sep 7, 2026

Stored XSS in W3 Total Cache 2.10.5 and earlier allows remote attackers to execute scripts through crafted comment content. The LazyLoad background mutator treats background-style text inside other HTML attributes as top-level style content, rewrites it, and turns inert approved comment markup into executable HTML. Exposure requires Lazy Load Images and Process background images to be enabled, plus moderator approval of the malicious comment and a later page view.

CVSS severity7.2
High
EPSS probability0.29%
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 2.10.5 and earlier allows remote attackers to execute scripts through crafted comment content. The LazyLoad background mutator treats background-style text inside other HTML attributes as top-level style content, rewrites it, and turns inert approved comment markup into executable HTML. Exposure requires Lazy Load Images and Process background images to be enabled, plus moderator approval of the malicious comment and a later page view.

The record

CVE
CVE-2026-78438
Published
Sep 5, 2026
Updated
Sep 7, 2026
Vendor
Web Ventures
Product
W3 Total Cache
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 7, 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 <=2.10.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Web Ventures · W3 Total Cacheversion=0 <=2.10.5

Published CVSS scores

7.2Wordfence CNACVSS:3.1/AV:N/AC:L/PR:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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