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

Am I affected?

• Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under a3 Lazy Load.
• No admin access? Run a passive check of your site. It reads public files only.

What to do

1. Update to version 2.7.7, or a newer patched version
2. Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
3. Watch a3 Lazy Load to get an email when the next vulnerability is published.

Advisory

Source description from Wordfence Intelligence, credited to theviper17y.

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.

Exploits & references

Proof-of-concept & detection

No public proof-of-concept or detection template is known for this vulnerability.

Advisories & patches

• Advisorywordfence.com

Related CVEs

Timeline

1. May 27, 2026

   CVE published

   Severity medium, CVSS 6.4

2. Nov 13, 2026

   Record last updated