CVE-2026-34076: Clerk JavaScript: SSRF in the opt-in clerkFrontendApiProxy feature may leak secret keys to unintended host

Clerk JavaScript is the official JavaScript repository for Clerk authentication. In @clerk/hono from versions 0.1.0 to before 0.1.5, @clerk/express from versions 2.0.0 to before 2.0.7, @clerk/backend from versions 3.0.0 to before 3.2.3, and @clerk/fastify from versions 3.1.0 to before 3.1.5, the clerkFrontendApiProxy function in @clerk/backend is vulnerable to Server-Side Request Forgery (SSRF). An unauthenticated attacker can craft a request path that causes the proxy to send the application's Clerk-Secret-Key to an attacker-controlled server. This issue has been patched in @clerk/hono version 0.1.5, @clerk/express version 2.0.7, @clerk/backend version 3.2.3, and @clerk/fastify version 3.1.5.