a3 Lazy Load: Cross-site scripting

a3 Lazy Load is affected by cross-site scripting. Exploitation requires an authenticated contributor account. Injected script can execute in the affected site's origin when the vulnerable output is viewed. The published affected range is <= 2.7.6.

CVE / CNA score 6.4 CVSS 3.1 · security@wordfence.com

NVD score Pending NVD has not published its own CVSS assessment.

Component: a3 Lazy Load
Plugin slug: a3-lazy-load
Affected: <= 2.7.6
Safe version: See mitigation notes
Published: May 28, 2026
Weakness: CWE-79 — Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

This CVE was published May 28, 2026 and is one of 2 known issues for this plugin.

What to do

Update, patch or deactivate.

No fixed release is identified. Update a3 Lazy Load when a release after 2.7.6 becomes available; until then, disable and remove it when the site's risk warrants. The official upstream changelog lists version 2.7.9, which is newer than the published affected range. Its changelog does not clearly confirm this specific fix, so it is not counted as a known-safe release.

No confirmed safe version is listed. Consider a vendor-supported patch or temporarily restricting the affected functionality while you assess the risk.

Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.

Source record

Technical 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.

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

References

Primary and upstream sources

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