CVE-2026-41248 — @clerk/nextjs
CRITICALCVE-2026-41248 is a critical-severity (CVSS 9.1) CWE-436 vulnerability in @clerk/nextjs. A fix is available for @clerk/nextjs — see the affected versions and patch details below.
Official Clerk JavaScript SDKs: Middleware-based route protection bypass
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-41248.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-41248 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
@clerk/nextjsnpm@clerk/nuxtnpm@clerk/astronpmDescription
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
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @clerk/nextjs | ≥ 5.0.0&&< 5.7.6 | 5.7.6npm install @clerk/nextjs@5.7.6 |
| 📦npm | @clerk/nuxt | ≥ 1.1.0&&< 1.13.28 | 1.13.28npm install @clerk/nuxt@1.13.28 |
| 📦npm | @clerk/astro | ≥ 0.0.1&&< 1.5.7 | 1.5.7npm install @clerk/astro@1.5.7 |
| 📦npm | @clerk/shared | ≥ 2.20.17&&< 2.22.1 | 2.22.1npm install @clerk/shared@2.22.1 |
| 📦npm | @clerk/nextjs | ≥ 6.0.0-snapshot.vb87a27f&&< 6.39.2 | 6.39.2npm install @clerk/nextjs@6.39.2 |
| 📦npm | @clerk/nextjs | ≥ 7.0.0&&< 7.2.1 | 7.2.1npm install @clerk/nextjs@7.2.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @clerk/nextjs, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @clerk/nextjs to 5.7.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41248 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-41248 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-41248. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-41248 in your dependencies?
O3 Security finds CVE-2026-41248 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.