GHSA-9mp4-77wg-rwx9
HIGH@clerk/backend Performs Insufficient Verification of Data Authenticity
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.
Blast Radius
@clerk/backend📦@clerk/astro📦@clerk/express📦@clerk/fastify📦@clerk/nextjs📦@clerk/nuxt📦@clerk/react-router📦@clerk/remix+1 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
Impact
Applications that use the verifyWebhook() helper to verify incoming Clerk webhooks are susceptible to accepting improperly signed webhook events.
Patches
@clerk/backend: the helper has been patched as of2.4.0@clerk/astro: the helper has been patched as of2.10.2@clerk/express: the helper has been patched as of1.7.4@clerk/fastify: the helper has been patched as of2.4.4@clerk/nextjs: the helper has been patched as of6.23.3@clerk/nuxt: the helper has been patched as of1.7.5@clerk/react-router: the helper has been patched as of1.6.4@clerk/remix: the helper has been patched as of4.8.5@clerk/tanstack-react-start: the helper has been patched as of0.18.3
Resolution
The issue was resolved in @clerk/backend 2.4.0 by:
- Properly parsing the webhook request's signatures and comparing them against the signature generated from the received event
Workarounds
If unable to upgrade, developers can workaround this issue by verifying webhooks manually, per this documentation.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @clerk/backend | ≥ 2.0.0&&< 2.4.0 | 2.4.0 |
| 📦npm | @clerk/astro | ≥ 2.9.0&&< 2.10.2 | 2.10.2 |
| 📦npm | @clerk/express | ≥ 1.6.0&&< 1.7.4 | 1.7.4 |
| 📦npm | @clerk/fastify | ≥ 2.3.0&&< 2.4.4 | 2.4.4 |
| 📦npm | @clerk/nextjs | ≥ 6.2.10&&< 6.23.3 | 6.23.3 |
| 📦npm | @clerk/nuxt | ≥ 1.7.0&&< 1.7.5 | 1.7.5 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @clerk/backend. 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/backend to 2.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9mp4-77wg-rwx9 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 GHSA-9mp4-77wg-rwx9 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 GHSA-9mp4-77wg-rwx9. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-9mp4-77wg-rwx9 in your dependencies?
O3 detects GHSA-9mp4-77wg-rwx9 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.