CVE-2026-8981

Lazy Blocks < 4.3.0 - Admin+ Stored XSS via Custom Block Frontend HTML

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.

Affected

Custom Block Builder

CVSS v3.1 CNA

3.5 LOWCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:L/A:N

EPSS

0.24% chance of exploitation in the next 30 days, 14th percentile

Published

2026-06-09

Proof-of-concept exploits (1)

• https://wpscan.com/vulnerability/9815b0e6-e411-4a5c-9c63-30bad21da698/

References

• CVE Record
• NVD entry