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.

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Fixes

Solution

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Workaround

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History

Tue, 09 Jun 2026 11:30:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 3.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:L/A:N'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 09 Jun 2026 09:15:00 +0000

Type Values Removed Values Added
First Time appeared Custom Block Builder
Custom Block Builder custom Block Builder
Wordpress
Wordpress wordpress
Vendors & Products Custom Block Builder
Custom Block Builder custom Block Builder
Wordpress
Wordpress wordpress

Tue, 09 Jun 2026 07:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-79

Tue, 09 Jun 2026 06:15:00 +0000

Type Values Removed Values Added
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.
Title Lazy Blocks < 4.3.0 - Admin+ Stored XSS via Custom Block Frontend HTML
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: WPScan

Published:

Updated: 2026-06-09T10:32:50.766Z

Reserved: 2026-05-19T13:11:53.990Z

Link: CVE-2026-8981

cve-icon Vulnrichment

Updated: 2026-06-09T10:32:43.295Z

cve-icon NVD

Status : Deferred

Published: 2026-06-09T06:16:54.067

Modified: 2026-06-09T13:51:18.770

Link: CVE-2026-8981

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-09T13:00:05Z

Weaknesses