XSS in Autoptimize

CVE-2026-3220

The Autoptimize WordPress plugin before 3.1.15, Clearfy Cache WordPress plugin before 2.4.2, Speed Optimizer WordPress plugin before 7.7.9 are vulnerable to unauthenticated Stored Cross-Site Scripting (XSS) due to a predictable replacement hash used during the HTML minification process and abusing a regular expression. This allows an attacker to inject arbitrary HTML attributes in the final HTML output by anticipating the placeholder format.

Vulnerability class: XSS (Cross-Site Scripting)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.004 (36.9th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 36.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-3220: held from 0.003 to 0.004.

EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001

Affected products

  • Autoptimize — versions 0
  • Clearfy Cache — versions 0
  • Speed Optimizer — versions 0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-3220?
CVE-2026-3220 is a high-severity vulnerability in Autoptimize, classified under Cross-site Scripting. CVSS score: 8.8/10. Published 2026-05-18.
How severe is CVE-2026-3220?
High severity. CVSS v3 base score is 8.8 out of 10.