CVE-2026-87920

W3 Total Cache <= 2.10.6 - Unauthenticated Stored Cross-Site Scripting via Comment Content

2026-10-01 21:12
theviper17y

Strategic Overview

Status
Patched in 2.10.7
Affected Plugin
W3 Total Cache
Affected Version
<= 2.10.6
CVSS
7.2High
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE-2026-87920
View all W3 Total Cache vulnerabilities

At a glance

CVE-2026-87920 is a high-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the W3 Total Cache WordPress plugin, affecting versions <= 2.10.6. It carries a CVSS score of 7.2 (reachable over the network; low attack complexity). Exploitation requires no authentication. The issue is fixed in version 2.10.7; sites on affected versions should update now. Disclosed October 2026, reported by theviper17y.

Vulnerability Overview

The W3 Total Cache plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Comment Content via Output-Buffer Regex Rewrite in all versions up to, and including, 2.10.6 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 vulnerability is only exploitable when the 'Remove query strings from static resources' option is enabled in W3 Total Cache, as mutate_url() must strip the '?' delimiter and everything following it — including the closing quote of the outer attribute — to break the attribute boundary.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user.

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

W3 Total Cache <= 2.10.6 carries this weakness at mutate_url(), and reaching it takes no account at all. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.

Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For W3 Total Cache the fix is 2.10.7: builds <= 2.10.6 are affected, anything from 2.10.7 onward is not.

Remediation

Update to version 2.10.7, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: W3 Total Cache 2.10.7 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Login Security
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-87920https://www.wordfence.com/threat-intel/vulnerabilities/id/34bd7c32-f4c5-4015-909a-e4730f35494bhttps://nvd.nist.gov/vuln/detail/CVE-2026-87920

Related records

Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C