Vulnerability · Published Apr 1, 2026 · Assigned by GitHub_M

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

High 7.4

In plain English

A high-severity server-side request forgery in javascript from clerk. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 25% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.4High

Exploit odds (30 days)0.3%top 74.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	@clerk/backend	3.2.3	GHSA-gjxx-92w9-8v8f
npm	@clerk/express	2.0.7	GHSA-gjxx-92w9-8v8f
npm	@clerk/fastify	3.1.5	GHSA-gjxx-92w9-8v8f
npm	@clerk/hono	0.1.5	GHSA-gjxx-92w9-8v8f

Affected products (as reported)

Vendor	Product	Versions
clerk	javascript	@clerk/hono >= 0.1.0, < 0.1.5@clerk/express >= 2.0.0, < 2.0.7@clerk/backend >= 3.0.0, < 3.2.3@clerk/fastify >= 3.1.0, < 3.1.5

Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

References

https://github.com/clerk/javascript/security/advisories/GHSA-gjxx-92w9-8v8f x_refsource_CONFIRM