Cross-Site Scripting (XSS) in concrete5/concrete5 (CVE-2026-8139)
Summary
Cross-site scripting in concrete5/concrete5 (CVE-2026-8139). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 9.5.1 or later.
Original description
The description as published by the source.
Concrete CMS 9.5.0 and below is vulnerable to Stored XSS via external-link page cvName because updateCollectionAliasExternal bypasses being sanitized.
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-2026-8139 has been found in concrete5/concrete5.
Risk of unauthorized operations or information disclosure. CVSS score: 5.4/10.
What to do: upgrade concrete5/concrete5 to 9.5.1 or later.
If unsure, ask your IT team or search "concrete5/concrete5 CVE-2026-8139" on the vendor's site.
CVE-2026-8139 (concrete5/concrete5) — CWE-79 / CVSS v3 5.4
Attack vector: remote (network-reachable)
Patched: 9.5.1 — apply immediately
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 concrete5/concrete5.
Check the vendor advisory for the affected versions of concrete5/concrete5.
Severity: Medium (CVSS 5.4/10). Risk of unauthorized operations or information disclosure.
Update to 9.5.1.
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. Run grep -r 'concrete5/concrete5' . against your dependency files (package-lock.json, requirements.txt, go.sum) 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
grep -r 'concrete5/concrete5' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
concrete5/concrete5を grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade concrete5/concrete5 to 9.5.1ステージング環境で 9.5.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-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。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web documentation.concretecms.org
- web github.com