CVE-2026-8981 Lazy Blocks < 4.3.0 - Admin+ Stored XSS via Custom Block Frontend HTML
Administrators can inject arbitrary JavaScript into block templates, leading to stored XSS for site visitors.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-8981?
CVE-2026-8981 is a low-severity cross-site scripting vulnerability in Unknown Custom Block Builder, published on 9 Jun 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Official description
The Custom Block Builder WordPress plugin before 4.3.0 does not consistently check the unfiltered_html capability across all paths that write to its block template code fields, allowing administrators on multisite installations (or single-site installs with DISALLOW_UNFILTERED_HTML defined) to inject arbitrary JavaScript that executes for any visitor of pages embedding the affected block.
Weakness: CWE-79
Which versions are affected by CVE-2026-8981?
How do I fix CVE-2026-8981?
No fix has been published for CVE-2026-8981 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-2026-8981 being exploited?
There is no known exploitation of CVE-2026-8981 in the wild and no public exploit code.
Sources
Also known as GHSA-cfcv-65jq-76jw.