Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

Go to Calendar     Go to Press Room     Go to Newsletters subscription

Search

CVE-2026-8981

Severity CVSS v4.0:
Pending analysis
Type:
CWE-79 Cross-Site Scripting (XSS)
Publication date:
09/06/2026
Last modified:
09/06/2026

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.

Impact

Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:L/A:N CVSS v3.1 Severity and Metrics:

Base Score: 3.50 LOW
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:L/A:N

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): High
User Interaction (UI): Required
Scope (S): Unchanged
Confidentiality (C): Low
Integrity (I): Low
Availability (A): None

Base Score 3.x
3.50
Severity 3.x
LOW

References to Advisories, Solutions, and Tools