CVE-2026-6427: 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 ...

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.

Metrics

CVSS 3.1

6.4/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

EPSS Probability

0.29%

20.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

References

Timeline

Published: May 28, 2026
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-6427?

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.

How severe is CVE-2026-6427?

CVE-2026-6427 has a CVSS score of 6.4/10 (MEDIUM severity). The EPSS model estimates a 0.29% probability of exploitation in the next 30 days.

How do I fix CVE-2026-6427?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.