---
id: CVE-2026-78438
title: >-
  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…
summary: >-
  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…
severity: high
cvss: 7.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N'
cwe:
  - CWE-79
published: '2026-09-05'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T13:12:58.310'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-78438'
references:
  - url: >-
      https://plugins.trac.wordpress.org/browser/w3-total-cache/tags/2.10.5/UserExperience_LazyLoad_Mutator.php#L255
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/w3-total-cache/tags/2.10.5/UserExperience_LazyLoad_Mutator.php#L293
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/w3-total-cache/tags/2.10.5/UserExperience_LazyLoad_Mutator.php#L91
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/w3-total-cache/tags/2.10.5/UserExperience_LazyLoad_Plugin.php#L87
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/changeset/3680101/w3-total-cache/tags/2.10.6/UserExperience_LazyLoad_Mutator.php
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/changeset?old_path=%2Fw3-total-cache/tags/2.10.5&new_path=%2Fw3-total-cache/tags/2.10.6
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/changeset?reponame=&new=3680101%40w3-total-cache%2Ftags%2F2.10.6&old=3653442%40w3-total-cache%2Ftags%2F2.10.5
    label: security@wordfence.com
  - url: >-
      https://www.wordfence.com/threat-intel/vulnerabilities/id/5580ad05-af50-4899-9cbf-39ad8000eb6a?source=cve
    label: security@wordfence.com
tags:
  - nvd
epss: 0.00287
epssPercentile: 0.21408
ingestedAt: '2026-09-06T03:49:20.023Z'
---

## 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.