CVE-2026-6427 a3 Lazy Load <= 2.7.6 - Authenticated (Contributor+) Stored Cross-Site Scripting via Video Element

Q: What is CVE-2026-6427?

CVE-2026-6427 is a medium-severity cross-site scripting vulnerability in a3rev a3 Lazy Load, published on 28 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Medium 6.4 Published 28 May 2026 Updated 28 May 2026

Authenticated contributors can inject malicious scripts via crafted video tags, allowing code execution in administrators' browsers.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-6427?

CVE-2026-6427 is a medium-severity cross-site scripting vulnerability in a3rev a3 Lazy Load, published on 28 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

The a3 Lazy Load plugin for WordPress is vulnerable to Stored Cross-Site Scripting in all versions up to, and including, 2.7.6 This is due to a regex bug in the _filter_videos() method that breaks HTML attribute quoting when processing crafted <video> elements, combined with unescaped output in the admin/views/form-data.php template. An authenticated attacker with Contributor-level access can insert a crafted <video> tag whose src attribute contains an embedded class=" substring that tricks the plugin's class-replacement regex into consuming an attribute-value closing quote. This shifts the HTML5 parser's quote boundary, promoting attacker-controlled text from inside a quoted attribute value into standalone event-handler attributes (autofocus, onfocus). The injected script executes in the browser of any user (including administrators) who views the post.

Weakness: CWE-79

Which versions are affected by CVE-2026-6427?

How do I fix CVE-2026-6427?

No fix has been published for CVE-2026-6427 yet. Limit exposure of the affected software until one is available.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2026-6427 being exploited?

There is no known exploitation of CVE-2026-6427 in the wild and no public exploit code.

Sources

Also known as GHSA-xgw3-j63x-rv92.