Cross-Site Scripting (XSS) in react-router (CVE-2026-53667)
Summary
Cross-site scripting in react-router (CVE-2026-53667). Confidential information can be exposed externally. Mitigation: upgrade to 7.18.0 or later.
Original description
The description as published by the source.
This is a follow up to https://github.com/remix-run/react-router/security/advisories/GHSA-8646-j5j9-6r62. React Router was alerted of a code path in the (unstable) RSC error handling path in which redirects from untrusted sources could still result in an XSS vector via attacker-supplied redirect targets
[!NOTE]
This only affects your application if you are using the unstable RSC APIs
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-2026-53667 has been found in react-router.
Confidential information can be exposed externally. CVSS score: 6.9/10.
What to do: upgrade react-router to 7.18.0 or later.
If unsure, ask your IT team or search "react-router CVE-2026-53667" on the vendor's site.
CVE-2026-53667 (react-router) — CWE-79 / CVSS v3 6.9
Attack vector: remote (network-reachable) / unauthenticated
Patched: 7.18.0 — 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 react-router.
Check the vendor advisory for the affected versions of react-router.
Severity: Medium (CVSS 6.9/10). Confidential information can be exposed externally.
Update to 7.18.0.
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 'react-router' . 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 'react-router' . | 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
react-router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 react-router to 7.18.0ステージング環境で 7.18.0 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。
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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。