Official Clerk JavaScript SDKs: Middleware-based route protection bypass - @clerk/shared

Description

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.

Sessions are not compromised and no existing user can be impersonated - the bypass only affects the middleware-level gating decision.

Recommendation

Update the @clerk/shared package to the latest compatible version. Followings are version details:

• Affected version(s): **>= 4.0.0, < 4.8.1

  >= 3.0.0-canary.v20250225091530, < 3.47.4

  >= 2.20.17, < 2.22.1**

• Patched version(s): **4.8.1

  3.47.4

  2.22.1**

References

• GHSA-vqx2-fgx2-5wq9
• CVE-2026-41248
• CWE-436
• CWE-863
• CAPEC-310
• OWASP 2021-A1
• OWASP 2021-A6

Related Issues

• Official Clerk JavaScript SDKs: Middleware-based route protection bypass - @clerk/nextjs - CVE-2026-41248
• Official Clerk JavaScript SDKs: Middleware-based route protection bypass - @clerk/astro - CVE-2026-41248
• Official Clerk JavaScript SDKs: Middleware-based route protection bypass - CVE-2026-41248
• Clerk has an authorization bypass when combining organization, billing, or reverification checks - @clerk/shared - CVE-2026-42349

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Tags:

npm

@clerk/shared