CVE-2026-40181
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedReact Router is a router for React. In versions 7.0.0 through 7.14.0 and 6.7.0 through 6.30.3, certain URLs passed to the redirect function can trigger an open redirect to an external domain due to path values starting with // being reinterpreted as protocol-relative URLs. The level of impact depends on the validation done by the application prior to returning the redirect. This does not impact applications using Declarative Mode (<BrowserRouter>). This is patched in versions 7.14.1 and 6.30.4.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceReact Router versions 7.0.0-7.14.0 and 6.7.0-6.30.3 contain an open redirect vulnerability in the redirect function. URLs starting with // are incorrectly interpreted as protocol-relative URLs, allowing redirection to external malicious domains. This only affects applications using Programmatic Mode, not Declarative Mode with <BrowserRouter>.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data>= 6.7.0, < 6.30.4>= 7.0.0, < 7.14.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check installed React Router versionRun 'npm list react-router' or 'npm list react-router-dom' to see the installed version. For Shopify React Router, check package.json dependencies.Affected if Version is 7.0.0-7.14.0 or 6.7.0-6.30.3 (or below 7.14.1/6.30.4)
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Verify routing configuration modeExamine your main router setup file (typically App.tsx, App.js, or router.tsx). Check whether you are using Declarative Mode with <BrowserRouter> wrapping <Routes> elements versus Programmatic Mode using createBrowserRouter with router.navigate() or redirect() calls.Affected if Using Programmatic Mode with createBrowserRouter/redirect() function rather than Declarative Mode with <BrowserRouter> and <Navigate> components
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Identify redirect function usageSearch codebase for calls to 'redirect()' function from react-router-dom (e.g., grep 'redirect(' or look for Action functions returning redirect responses). Identify if redirect URLs come from user input, query parameters, or external sources.Affected if Code passes dynamically constructed or user-supplied URLs to the redirect() function without validation
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Check for URL validation before redirectReview redirect handler code to see if URLs are validated before being passed to redirect(). Look for validation logic that rejects URLs starting with '//' or rejects external domains.Affected if No validation exists, or validation does not explicitly block URLs starting with '//' or external domains
You are affected if you have React Router versions 6.7.0-6.30.3 or 7.0.0-7.14.0 AND use Programmatic Mode with redirect() function handling external or user-supplied URLs without validating that they do not start with '//'.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped6.30.47.14.1
Upgrade React Router to version 7.14.1 or 6.30.4, or migrate to Declarative Mode (<BrowserRouter>), or implement strict URL validation before passing to the redirect function.
[email protected] for v6.x branch or [email protected] for v7.x branch
- 1. Identify which React Router version is currently installed in your project by checking package.json or package-lock.json
- 2. Determine which major version branch you are on (v6 or v7) based on your current version
- 3. Run the appropriate upgrade command for your package manager: npm install [email protected] (for v6) or npm install [email protected] (for v7), or yarn add [email protected] / [email protected]
- 4. Verify the upgrade was successful by checking the installed version with npm list react-router
- 5. Test your application's redirect functionality to confirm the vulnerability is resolved and normal redirects still work as expected
- 6. If you are on v6 and considering moving to v7, review the v7 migration guide for any breaking changes before upgrading further
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-40181 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-40181 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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