CVE-2026-34076
Clerk: SSRF in the opt-in clerkFrontendApiProxy feature may leak secret keys to unintended host
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | @clerk/backend | >= 3.0.0, <= 3.2.2 | 3.2.3 |
| npm | @clerk/express | >= 2.0.0, <= 2.0.6 | 2.0.7 |
| npm | @clerk/hono | >= 0.1.0, <= 0.1.4 | 0.1.5 |
| npm | @clerk/fastify | >= 3.1.0, <= 3.1.4 | 3.1.5 |
Affected products
| Product | Affected versions |
|---|---|
| And @Clerk/Fastify From Versions 3.1.0 To | before 3.1.5 |
Versions were read from the advisory text. No structured product data has been published for this record yet.