Cross-Site Scripting (XSS) in Custom Block Builder (WordPress plugin) (CVE-2026-8981)
Summary
Cross-site scripting in Custom Block Builder (WordPress plugin) (CVE-2026-8981). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-8981 has been found in Custom Block Builder (WordPress plugin).
Risk of unauthorized operations or information disclosure. CVSS score: 3.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Custom Block Builder (WordPress plugin) CVE-2026-8981" on the vendor's site.
CVE-2026-8981 (Custom Block Builder (WordPress plugin)) — CWE-79 / CVSS v3 3.5
Attack vector: remote (network-reachable)
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Cross-site scripting (XSS) (CWE-79) exists in Custom Block Builder (WordPress plugin).
Check the vendor advisory for the affected versions of Custom Block Builder (WordPress plugin).
Severity: Low (CVSS 3.5/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Custom Block Builder (WordPress plugin) を使っているサービスとバージョンを洗い出す。
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2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
References
- web contact@wpscan.com
- web nvd.nist.gov
- web wpscan.com
- web github.com