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CVE-2026-46609
medium
CVSS 4.6
Cross-Site Scripting (XSS) in Umbraco.Cms (CVE-2026-46609)
Summary
cross-site scripting in Umbraco.Cms (CVE-2026-46609). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to `17.4.0` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-46609** has been found in Umbraco.Cms.
Risk of unauthorized operations or information disclosure. CVSS score: 4.6/10.
What to do: upgrade Umbraco.Cms to **17.4.0** or later.
If unsure, ask your IT team or search "Umbraco.Cms CVE-2026-46609" on the vendor's site.
CVE-2026-46609 (Umbraco.Cms) — CWE-79 / CVSS v3 4.6
Attack vector: remote (network-reachable)
Patched: `17.4.0` — 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.
❓ What is the problem
**Cross-site scripting (XSS)** (CWE-79) exists in Umbraco.Cms.
📍 Affected scope
Umbraco.Cms — .
🔥 Severity
Severity: Medium (CVSS 4.6/10). Risk of unauthorized operations or information disclosure
🔧 How to fix
Update to **17.4.0**.
🛡️ Workaround
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'Umbraco.Cms' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response Actions (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'Umbraco.Cms' . | 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 `Umbraco.Cms` を grep し、稼働しているサービス・バージョンを把握する。
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6Apply patch patch
Upgrade Umbraco.Cms to 17.4.0ステージング環境で 17.4.0 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と、Step 3 で見つけた異常検知の続報チェックを含めること。
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7Post-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 Step 3 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
nuget
Umbraco.Cms
[{"type":"ECOSYSTEM","events":[{"introduced":"14.0.0"},{"fixed":"17.4.0"}]}]