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High severity · published Sep 5, 2026
CVE-2026-78438
W3 Total Cache <= 2.10.5 - Unauthenticated Stored Cross-Site Scripting via LazyLoad Background Mutator
7.2
CVSS
0.5%
EPSS
No
On KEV
Description
The W3 Total Cache plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Comment Content via LazyLoad Background Mutator in all versions up to, and including, 2.10.5 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This requires the "Lazy Load Images" feature with "Process background images" to be enabled, and the malicious comment to be approved by a moderator before execution is triggered.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 43% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
WT
W3 Total Cache · boldgrid
through 2.10.5 · source: vendor
Affected product
WT
W3 Total Cache
boldgrid
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-78438
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-78438
plugins.trac.wordpress.org
https://plugins.trac.wordpress.org/browser/w3-total-cache/tags/2.10.5/UserExperience_LazyLoad_Mutator.php#L255
plugins.trac.wordpress.org
https://plugins.trac.wordpress.org/browser/w3-total-cache/tags/2.10.5/UserExperience_LazyLoad_Mutator.php#L293
plugins.trac.wordpress.org
https://plugins.trac.wordpress.org/browser/w3-total-cache/tags/2.10.5/UserExperience_LazyLoad_Mutator.php#L91
plugins.trac.wordpress.org
https://plugins.trac.wordpress.org/browser/w3-total-cache/tags/2.10.5/UserExperience_LazyLoad_Plugin.php#L87
plugins.trac.wordpress.org
https://plugins.trac.wordpress.org/changeset/3680101/w3-total-cache/tags/2.10.6/UserExperience_LazyLoad_Mutator.php
plugins.trac.wordpress.org
https://plugins.trac.wordpress.org/changeset?old_path=%2Fw3-total-cache/tags/2.10.5&new_path=%2Fw3-total-cache/tags/2.10.6
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