# CVE-2026-41248: Official Clerk JavaScript SDKs: Middleware-based route protection bypass > Attackers can bypass middleware route protection in Clerk JavaScript SDKs to access restricted handlers, requiring an upgrade to patched versions. - **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 24 Apr 2026 - **Updated:** 27 Apr 2026 - **Also known as:** GHSA-vqx2-fgx2-5wq9 ## What is CVE-2026-41248? CVE-2026-41248 is a critical authentication bypass vulnerability in clerk astro, published on 24 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description 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 Weakness: CWE-863 (Incorrect Authorization), CWE-436 (Interpretation Conflict) ## Which versions are affected by CVE-2026-41248? 22 open source packages ship an affected version, including @clerk/astro, @clerk/nextjs and @clerk/nuxt. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `@clerk/astro` | npm | From 0.0.1 | 1.5.7 | | `@clerk/astro` | npm | From 0.0.1 | 1.5.7 | | `@clerk/astro` | npm | From 2.0.0-snapshot.v20241206174604 | 2.17.10 | | `@clerk/astro` | npm | From 2.0.0-snapshot.v20241206174604 | 2.17.10 | | `@clerk/astro` | npm | From 3.0.0 | 3.0.15 | | `@clerk/astro` | npm | From 3.0.0 | 3.0.15 | | `@clerk/nextjs` | npm | From 5.0.0 | 5.7.6 | | `@clerk/nextjs` | npm | From 5.0.0 | 5.7.6 | | `@clerk/nextjs` | npm | From 6.0.0-snapshot.vb87a27f | 6.39.2 | | `@clerk/nextjs` | npm | From 6.0.0-snapshot.vb87a27f | 6.39.2 | | `@clerk/nextjs` | npm | From 7.0.0 | 7.2.1 | | `@clerk/nextjs` | npm | From 7.0.0 | 7.2.1 | | `@clerk/nuxt` | npm | From 1.1.0 | 1.13.28 | | `@clerk/nuxt` | npm | From 1.1.0 | 1.13.28 | | `@clerk/nuxt` | npm | From 2.0.0 | 2.2.2 | | `@clerk/nuxt` | npm | From 2.0.0 | 2.2.2 | | `@clerk/shared` | npm | From 2.20.17 | 2.22.1 | | `@clerk/shared` | npm | From 2.20.17 | 2.22.1 | | `@clerk/shared` | npm | From 3.0.0-canary.v20250225091530 | 3.47.4 | | `@clerk/shared` | npm | From 3.0.0-canary.v20250225091530 | 3.47.4 | | `@clerk/shared` | npm | From 4.0.0 | 4.8.1 | | `@clerk/shared` | npm | From 4.0.0 | 4.8.1 | ## How do I fix CVE-2026-41248? Upgrade @clerk/astro to a fixed version for your release line: 1.5.7, 2.17.10 or 3.0.15. ## Is CVE-2026-41248 being exploited? There is no known exploitation of CVE-2026-41248 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-41248 and fix it if it is affected. What it is: CVE-2026-41248 is a critical authentication bypass vulnerability in clerk astro, published on 24 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-41248 in the wild and no public exploit code. Affected packages and fixed versions: - @clerk/astro (npm): affected from 0.0.1; fixed in 1.5.7 - @clerk/astro (npm): affected from 0.0.1; fixed in 1.5.7 - @clerk/astro (npm): affected from 2.0.0-snapshot.v20241206174604; fixed in 2.17.10 - @clerk/astro (npm): affected from 2.0.0-snapshot.v20241206174604; fixed in 2.17.10 - @clerk/astro (npm): affected from 3.0.0; fixed in 3.0.15 - @clerk/astro (npm): affected from 3.0.0; fixed in 3.0.15 - @clerk/nextjs (npm): affected from 5.0.0; fixed in 5.7.6 - @clerk/nextjs (npm): affected from 5.0.0; fixed in 5.7.6 - @clerk/nextjs (npm): affected from 6.0.0-snapshot.vb87a27f; fixed in 6.39.2 - @clerk/nextjs (npm): affected from 6.0.0-snapshot.vb87a27f; fixed in 6.39.2 - @clerk/nextjs (npm): affected from 7.0.0; fixed in 7.2.1 - @clerk/nextjs (npm): affected from 7.0.0; fixed in 7.2.1 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-41248/ (Markdown: https://insights.sbomify.com/CVE-2026-41248/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-41248 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-41248 - OSV: https://osv.dev/vulnerability/CVE-2026-41248 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-41248/ Summaries are generated and may contain mistakes; the official description above is the record.