CVE-2026-34076 Clerk JavaScript: SSRF in the opt-in clerkFrontendApiProxy feature may leak secret keys to unintended host
An unauthenticated attacker can exploit an SSRF vulnerability in the opt-in proxy feature to leak secret keys to an external server.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-34076?
CVE-2026-34076 is a high-severity server-side request forgery vulnerability in clerk javascript, published on 1 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-918
Which versions are affected by CVE-2026-34076?
8 open source packages ship an affected version, including @clerk/backend, @clerk/express and @clerk/fastify.
| Package | Affected | Fixed in |
|---|---|---|
@clerk/backend npm | From 3.0.0 | 3.2.3 |
@clerk/backend npm | From 3.0.0 | 3.2.3 |
@clerk/express npm | From 2.0.0 | 2.0.7 |
@clerk/express npm | From 2.0.0 | 2.0.7 |
@clerk/fastify npm | From 3.1.0 | 3.1.5 |
@clerk/fastify npm | From 3.1.0 | 3.1.5 |
2 more packages
@clerk/hono npm | From 0.1.0 | 0.1.5 |
@clerk/hono npm | From 0.1.0 | 0.1.5 |
How do I fix CVE-2026-34076?
Upgrade @clerk/backend to 3.2.3 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-34076 being exploited?
There is no known exploitation of CVE-2026-34076 in the wild and no public exploit code.
Sources
Also known as GHSA-gjxx-92w9-8v8f.