---
title: "CVE-2026-41248: Official Clerk JavaScript SDKs: Middleware-based route protection bypass"
url: https://erroneo.us/security/cve/CVE-2026-41248/
description: "CVE-2026-41248 (@clerk/nextjs (npm)): Clerk JavaScript is the official JavaScript repository for Clerk authentication. createRouteMatcher in @clerk/nextjs…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-04-24
date_modified: 2026-04-27
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-41248"
kev: false
cvss: 9.1
epss: 0.00529
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-41248: Official Clerk JavaScript SDKs: Middleware-based route protection bypass

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.5% , percentile 44: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 44% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes @clerk/nextjs (npm) >= 5.0.0, < 5.7.6, fixed in 5.7.6 ; @clerk/nuxt (npm) >= 1.1.0, < 1.13.28, fixed in 1.13.28 ; @clerk/astro (npm) >= 0.0.1, < 1.5.7, fixed in 1.5.7 ; @clerk/shared (npm) >= 2.20.17, < 2.22.1, fixed in 2.22.1 . Check your lockfile, including transitive dependencies.

## What it is

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

## Affected packages

- npm `@clerk/nextjs` >= 5.0.0, < 5.7.6 → fixed: 5.7.6
- npm `@clerk/nuxt` >= 1.1.0, < 1.13.28 → fixed: 1.13.28
- npm `@clerk/astro` >= 0.0.1, < 1.5.7 → fixed: 1.5.7
- npm `@clerk/shared` >= 2.20.17, < 2.22.1 → fixed: 2.22.1
- npm `@clerk/nextjs` >= 6.0.0-snapshot.vb87a27f, < 6.39.2 → fixed: 6.39.2
- npm `@clerk/nextjs` >= 7.0.0, < 7.2.1 → fixed: 7.2.1
- npm `@clerk/nuxt` >= 2.0.0, < 2.2.2 → fixed: 2.2.2
- npm `@clerk/astro` >= 2.0.0-snapshot.v20241206174604, <= 2.17.9 → fixed: 2.17.10
- npm `@clerk/astro` >= 3.0.0, < 3.0.15 → fixed: 3.0.15
- npm `@clerk/shared` >= 3.0.0-canary.v20250225091530, < 3.47.4 → fixed: 3.47.4
- npm `@clerk/shared` >= 4.0.0, < 4.8.1 → fixed: 4.8.1

## Affected products (CVE record)

- clerk astro: >= 0.0.1, < 1.5.7, >= 2.0.0-snapshot.v20241206174604, <= 2.17.9, >= 3.0.0, < 3.0.15
- clerk nextjs: >= 5.0.0, < 5.7.6, >= 6.0.0-snapshot.vb87a27f, < 6.39.2, >= 7.0.0, < 7.2.1
- clerk nuxt: >= 1.1.0, < 1.13.28, >= 2.0.0, < 2.2.2
- clerk shared: >= 2.20.17, < 2.22.1, >= 3.0.0-canary.v20250225091530, < 3.47.4, >= 4.0.0, < 4.8.1

## Severity

- GitHub_M CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`
- GitHub CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.53% probability of exploitation activity in the next 30 days; percentile 44.

## Sources

- [GitHub Advisory GHSA-vqx2-fgx2-5wq9](https://github.com/advisories/GHSA-vqx2-fgx2-5wq9)
- [CVE.org record CVE-2026-41248](https://www.cve.org/CVERecord?id=CVE-2026-41248)
- [NVD entry CVE-2026-41248](https://nvd.nist.gov/vuln/detail/CVE-2026-41248)
- [github.com](https://github.com/clerk/javascript/security/advisories/GHSA-vqx2-fgx2-5wq9)

---
Source page: https://erroneo.us/security/cve/CVE-2026-41248/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt