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.
Original description
The description as published by the source.
Umbraco is an ASP.NET CMS. From version 14.0.0 to before version 17.4.0, authenticated users are able to inject HTML into an input field, which is rendered in the confirmation dialog without proper output encoding. This issue has been patched in version 17.4.0.
Source: GitHub Security Advisories (Global) 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-2026-46609 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.
Cross-site scripting (XSS) (CWE-79) exists in Umbraco.Cms.
Check the vendor advisory for the affected versions of Umbraco.Cms.
Severity: Medium (CVSS 4.6/10). Risk of unauthorized operations or information disclosure.
Update to 17.4.0.
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 'Umbraco.Cms' . 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 '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。 -
2Apply 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 github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com