Clerk · @Clerk/Express · CVE-2026-34076
Name of the Vulnerable Software and Affected Versions
@clerk/backend versions 3.0.0 through 3.2.2
@clerk/express versions 2.0.0 through 2.0.6
@clerk/hono versions 0.1.0 through 0.1.4
@clerk/fastify versions 3.1.0 through 3.1.4
Description
The `clerkFrontendApiProxy` function is susceptible to Server-Side Request Forgery (SSRF). An unauthenticated attacker can manipulate a request path to cause the proxy to transmit the application's `Clerk-Secret-Key` to a server controlled by the attacker. The vulnerability affects applications that have explicitly enabled the `frontendApiProxy` feature.
Recommendations
Upgrade to @clerk/backend version 3.2.3 or later.
Upgrade to @clerk/express version 2.0.7 or later.
Upgrade to @clerk/hono version 0.1.5 or later.
Upgrade to @clerk/fastify version 3.1.5 or later.
Rotate your Clerk Secret Key after upgrading.