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HIGH severity

CVE-2026-87920 — WordPress

HIGH

CVE-2026-87920 is a high-severity (CVSS 7.2) Cross-site Scripting (XSS) vulnerability. No vendor fix is recorded yet; mitigation options are listed below.

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…

Published
Oct 2, 2026
Updated
Oct 2, 2026
Affected
—
Patched
—
Exploits
None indexed
Exploitation data as of Oct 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Description

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.

Detection & mitigation playbook

Vulnerability

  1. Detect

    Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

  2. Remediation status

    No fixed release is recorded for CVE-2026-87920 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

  3. Mitigate without a patch

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

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
O3 Security · Impact-Aware SCA

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