CVE-2026-8981

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

Published Jun 9, 2026 CVSS 3.1 · 3.5 Low EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
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'}

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
Type Values Removed Values Added
Weaknesses CWE-79
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
Weaknesses

Sources

Status
PUBLISHED
Assigner
WPScan
Published
Updated
Jun 9, 2026, 10:32 AM
Reserved
May 19, 2026, 1:11 PM
Status
Deferred
Published
Jun 9, 2026, 6:16 AM
Modified
Jul 23, 2026, 8:10 AM