Quick answers
- Is CVE-2026-3220 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-3220 being exploited in the wild.
- How severe is CVE-2026-3220?
- Informational severity, with a CVSS score of 8.8, published 18 May 2026.
- Which products and versions are affected?
- Autoptimize < 3.1.15; Clearfy Cache < 2.4.2; SiteGround Speed Optimizer < 7.7.9.
- Is there a fix for CVE-2026-3220?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-3220 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-3220?
- Check whether you run Autoptimize, Clearfy Cache or SiteGround Speed Optimizer at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability exists in the HTML minification logic shared across multiple WordPress plugins (Autoptimize, Clearfy Cache, and Speed Optimizer). The root cause is the use of a predictable replacement hash and a flawed regular expression during the minification process. An unauthenticated attacker can anticipate the placeholder format used for minification to inject arbitrary HTML attributes and malicious JavaScript into the final rendered page. This results in Stored Cross-Site Scripting (XSS) that executes in the context of any user viewing the affected pages. Patches are available in Autoptimize 3.1.15, Clearfy 2.4.2, and Speed Optimizer 7.7.9.
Affected products
- Autoptimize Autoptimize < 3.1.15
- Clearfy Clearfy Cache < 2.4.2
- SiteGround Speed Optimizer (sg-cachepress) < 7.7.9
Timeline
- 2026-04-27: disclosed: Publicly published by researcher
- 2026-05-18: advisory: NVD publication date