What is CVE-2026-18109?

CVE-2026-18109 is a high-severity vulnerability in Boldgrid W3 Total Cache, classified under Cross-site Scripting. CVSS score: 7.2/10. Published 2026-08-14.

How severe is CVE-2026-18109?

High severity. CVSS v3 base score is 7.2 out of 10.

XSS in Boldgrid W3 Total Cache

CVE-2026-18109

The W3 Total Cache plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Comment Author Name in all versions up to, and including, 2.10.3 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 Lazy Load Images feature of W3 Total Cache is enabled, as the unsafe re-emission occurs exclusively within the LazyLoad mutator's img tag rewriting step.

Vulnerability class: XSS (Cross-Site Scripting)

CVSS v3 metric

CVSS v3 base score 7.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N.

Affected products

Boldgrid W3 Total Cache — versions 0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

Frequently asked questions

What is CVE-2026-18109?: CVE-2026-18109 is a high-severity vulnerability in Boldgrid W3 Total Cache, classified under Cross-site Scripting. CVSS score: 7.2/10. Published 2026-08-14.
How severe is CVE-2026-18109?: High severity. CVSS v3 base score is 7.2 out of 10.