CVE-2026-78438High· 7.2▾ Twilight

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 escap…

▾ Twilight zone — High severity, or a signal on a lesser flaw

Depth score40/ 100 · Moderate

impact 39.6 · likelihood 0.1 · exploitation 0

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Proof of concept

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Published

Sep 5, 2026

Updated

Sep 8, 2026

CVSS

7.2

Vendor

—

Product

—

CWE

CWE-79

Depth score

40 · Moderate

EPSS

0.29% · p21

Platforms

—

Source

NVD

Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

EPSS history

Exploit-prediction probability, daily snapshots since Sep 6.

0.3% → 0.3%

Timeline

Disclosure to exploitation, from the record and what we observed since indexing it.

3 events · 3 days

Sep 5, 2026Published
Disclosed via NVD
Sep 6, 2026EPSS first tracked
0.3%
Sep 8, 2026Record revised
Last analysed / modified upstream

CWE-79 #nvd

Full technical detail▾

Overview

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.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

References

Related vulnerabilities

Connected by shared product, vendor, weakness, or advisory.

#nvd

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