CVE-2025-53548
- Category
- Security
- Published
Summary
A vulnerability affecting @clerk/backend >= 2.0.0 < 2.4.0 was recently reported to the Clerk team and resolved. The vulnerability was discovered in the verifyWebhook() helper, which is used to verify incoming Clerk webhooks, and it allowed improperly signed webhook events to be accepted as legitimate. Potentially impacted customers have already been notified via email. If your application does not use verifyWebhook() you are not impacted.
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.
Credits
Thanks to a Clerk customer for responsibly disclosing the issue to the team.