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CWE-436Weakness · CWE-436

CVE-2026-41248

CRITICAL · 9.1 CVSS v3.1 Published 2026-04-24
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
Clerk JavaScript is the official JavaScript repository for Clerk authentication. createRouteMatcher in @clerk/nextjs, @clerk/nuxt, and @clerk/astro can be bypassed by certain crafted requests, allowing them to skip middleware gating and reach downstream handlers. This vulnerability is fixed in @clerk/astro 1.5.7, 2.17.10, and 3.0.15; @clerk/nextjs 5.7.6, 6.39.2, and 7.2.1; @clerk/nuxt 1.13.28 and 2.2.2; and @clerk/shared 2.22.1, 3.47.4, anc 4.8.1

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 confidence

The createRouteMatcher function in Clerk's JavaScript SDKs contains a logic flaw that allows crafted requests to bypass middleware authentication checks. Attackers can send specially constructed requests that circumvent the route matching logic, enabling unauthorized access to protected endpoints without proper authentication.

MitigationUpgrade @clerk/nextjs, @clerk/nuxt, @clerk/astro, and @clerk/shared to the fixed versions (6.39.2/7.2.1 for nextjs, 2.2.2 for nuxt, 3.0.15 for astro, 4.8.1 for shared) to remediate this vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS 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
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Clerk packages
    Run 'npm list @clerk/nextjs @clerk/nuxt @clerk/astro @clerk/shared' or inspect package.json to see which Clerk packages are installed and their current versions.
    Affected if Any of these packages are installed with versions below: nextjs < 6.39.2 or < 7.2.1, nuxt < 2.2.2, astro < 3.0.15, shared < 4.8.1
  2. Locate createRouteMatcher usage in middleware
    Search project files for 'createRouteMatcher' import and usage - typically in middleware.ts/js files under routes or src directories. Example: grep -r 'createRouteMatcher' .
    Affected if The createRouteMatcher function from @clerk/* SDKs is imported and used in middleware configuration files
  3. Verify middleware authentication is active
    Inspect the middleware file to confirm auth protection is applied. Look for patterns like 'authMiddleware', 'requireAuth', or ' clerk.authenticate()' wrapping routes.
    Affected if Middleware authentication checks are enabled and protecting routes using createRouteMatcher for route matching

User is affected if they have any vulnerable Clerk package version (nextjs <6.39.2/<7.2.1, nuxt <2.2.2, astro <3.0.15, shared <4.8.1) AND use createRouteMatcher in their auth middleware.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade @clerk/nextjs, @clerk/nuxt, @clerk/astro, and @clerk/shared to the fixed versions (6.39.2/7.2.1 for nextjs, 2.2.2 for nuxt, 3.0.15 for astro, 4.8.1 for shared) to remediate this vulnerability.

Recommended fix High confidence

@clerk/nextjs 7.2.1, @clerk/nuxt 2.2.2, @clerk/astro 3.0.15, and @clerk/shared 4.8.1 (or the appropriate version within your current major version branch as listed in the advisory)

  1. 1. Identify all @clerk packages currently installed in your project (e.g., run `npm list @clerk/nextjs @clerk/nuxt @clerk/astro @clerk/shared` or check package.json)
  2. 2. For @clerk/nextjs users: upgrade to version 7.2.1 (or 6.39.2 or 5.7.6 depending on your major version) using `npm install @clerk/nextjs@^7.2.1`
  3. 3. For @clerk/nuxt users: upgrade to version 2.2.2 (or 1.13.28 depending on your major version) using `npm install @clerk/nuxt@^2.2.2`
  4. 4. For @clerk/astro users: upgrade to version 3.0.15 (or 2.17.10 or 1.5.7 depending on your major version) using `npm install @clerk/astro@^3.0.15`
  5. 5. If @clerk/shared is used: upgrade to version 4.8.1 (or 3.47.4 or 2.22.1 depending on your major version) using `npm install @clerk/shared@^4.8.1`
  6. 6. Run your test suite to verify authentication middleware still functions correctly after the upgrade
  7. 7. Test that crafted requests that previously could bypass createRouteMatcher are now properly gated
Caveat May include breaking changes between major versions; review Clerk changelogs before upgrading across major version boundaries

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-41248 in production — separate from our analysis above.

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  • Version or environment caveats, and links to real fixes
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