CVE-2026-42349
CVE-2026-42349 is a security vulnerability in @clerk/shared. O3 Security confirms whether CVE-2026-42349 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Clerk: Authorization bypass when combining organization, billing, or reverification checks
Real-World Exposure
@clerk/shared📦@clerk/shared📦@clerk/backend📦@clerk/backend📦@clerk/nextjs📦@clerk/nextjs📦@clerk/clerk-js📦@clerk/clerk-js+21 moreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.
Description
Clerk JavaScript is the official JavaScript repository for Clerk authentication. has(), auth.protect(), and related authorization predicates in @clerk/shared, @clerk/nextjs, @clerk/backend, and other framework SDKs can return true for certain combined authorization checks when the result should be false, allowing a gated action to proceed for a user who does not satisfy the full set of requested conditions. This call shape can be bypassed if certain conditions are met: a has() or auth.protect() call that combines a reverification check with any of role, permission, feature, or plan, or that combines a billing check (feature or plan) with a role or permission check. This vulnerability is fixed in @clerk/clerk-js 5.125.10 and 6.7.5.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @clerk/shared | ≥ 3.0.0&&< 3.47.5 | 3.47.5 |
| 📦npm | @clerk/shared | ≥ 4.0.0&&< 4.8.3 | 4.8.3 |
| 📦npm | @clerk/backend | ≥ 2.0.0&&< 2.33.3 | 2.33.3 |
| 📦npm | @clerk/backend | ≥ 3.0.0&&< 3.2.14 | 3.2.14 |
| 📦npm | @clerk/nextjs | ≥ 6.0.0&&< 6.39.3 | 6.39.3 |
| 📦npm | @clerk/nextjs | ≥ 7.0.0&&< 7.2.4 | 7.2.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @clerk/shared. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @clerk/shared to 3.47.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42349 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 pinpoints whether CVE-2026-42349 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-42349. 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-2026-42349 in your dependencies?
O3 detects CVE-2026-42349 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.