@clerk/backend Performs Insufficient Verification of Data Authenticity

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 of 2.4.0
• @clerk/astro: the helper has been patched as of 2.10.2
• @clerk/express: the helper has been patched as of 1.7.4
• @clerk/fastify: the helper has been patched as of 2.4.4
• @clerk/nextjs: the helper has been patched as of 6.23.3
• @clerk/nuxt: the helper has been patched as of 1.7.5
• @clerk/react-router: the helper has been patched as of 1.6.4
• @clerk/remix: the helper has been patched as of 4.8.5
• @clerk/tanstack-react-start: the helper has been patched as of 0.18.3

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.