{"id":"CVE-2026-34076","aliases":["EUVD-2026-17974","GHSA-gjxx-92w9-8v8f"],"status":"published","title":"Clerk JavaScript: SSRF in the opt-in clerkFrontendApiProxy feature may leak secret keys to unintended host","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.","severity":{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00321,"percentile":0.25407,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-918"],"published":"2026-03-27T19:58:19Z","modified":"2026-10-28T02:30:39Z","fixes":[{"ecosystem":"npm","package":"@clerk/backend","fixed_in":["3.2.3"],"sources":["ghsa","osv"]},{"ecosystem":"npm","package":"@clerk/express","fixed_in":["2.0.7"],"sources":["ghsa","osv"]},{"ecosystem":"npm","package":"@clerk/hono","fixed_in":["0.1.5"],"sources":["ghsa","osv"]},{"ecosystem":"npm","package":"@clerk/fastify","fixed_in":["3.1.5"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"@clerk/backend","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.0"},{"last_affected":"3.2.2"},{"fixed":"3.2.3"}]}]},{"source":"ghsa","ecosystem":"npm","package":"@clerk/express","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.0.0"},{"last_affected":"2.0.6"},{"fixed":"2.0.7"}]}]},{"source":"ghsa","ecosystem":"npm","package":"@clerk/hono","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.1.0"},{"last_affected":"0.1.4"},{"fixed":"0.1.5"}]}]},{"source":"ghsa","ecosystem":"npm","package":"@clerk/fastify","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.1.0"},{"last_affected":"3.1.4"},{"fixed":"3.1.5"}]}]},{"source":"osv","ecosystem":"npm","package":"@clerk/backend","ranges":[{"type":"SEMVER","events":[{"introduced":"3.0.0"},{"fixed":"3.2.3"}]}]},{"source":"osv","ecosystem":"npm","package":"@clerk/express","ranges":[{"type":"SEMVER","events":[{"introduced":"2.0.0"},{"fixed":"2.0.7"}]}]},{"source":"osv","ecosystem":"npm","package":"@clerk/hono","ranges":[{"type":"SEMVER","events":[{"introduced":"0.1.0"},{"fixed":"0.1.5"}]}]},{"source":"osv","ecosystem":"npm","package":"@clerk/fastify","ranges":[{"type":"SEMVER","events":[{"introduced":"3.1.0"},{"fixed":"3.1.5"}]}]}],"products":[{"vendor":"clerk","product":"javascript"}],"references":[{"url":"https://github.com/clerk/javascript/security/advisories/GHSA-gjxx-92w9-8v8f","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-34076","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-gjxx-92w9-8v8f"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34076.json","tags":["advisory"]},{"url":"https://github.com/clerk/javascript","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-34076","title":"Clerk JavaScript: SSRF in the opt-in clerkFrontendApiProxy feature may leak secret keys to unintended host","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.","status":"published","published":"2026-04-01T16:59:21.828Z","modified":"2026-04-01T18:00:23.118Z","cvss":[{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-918"],"updated_at":"2026-11-02T14:20:13.962274Z"}],"euvd":[{"id":"EUVD-2026-17974","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.","status":"published","published":"2026-04-01T16:59:21Z","modified":"2026-04-01T18:00:23Z","cvss":[{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T19:25:24.09733Z"}],"ghsa":[{"id":"GHSA-gjxx-92w9-8v8f","title":"Clerk: SSRF in the opt-in clerkFrontendApiProxy feature may leak secret keys to unintended host","description":"## Summary\n\nThe `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.\n\n## Affected packages\n\nOnly applications that have opted into the `frontendApiProxy` feature are affected. This feature is not enabled by default. **Users of `@clerk/nextjs` are not affected** due to how the framework handles repeated `/` in request paths.\n\n| Package | Affected versions | Fixed version |\n|---|---|---|\n| `@clerk/backend` | `\u003e= 3.0.0, \u003c= 3.2.2` | `3.2.3` |\n| `@clerk/express` | `\u003e= 2.0.0, \u003c= 2.0.6` | `2.0.7` |\n| `@clerk/hono` | `\u003e= 0.1.0, \u003c= 0.1.4` | `0.1.5` |\n| `@clerk/fastify` | `\u003e= 3.1.0, \u003c= 3.1.4` | `3.1.5` |\n\nSearch your codebase for the `frontendApiProxy` option. If none of the patterns below appear in your code, you are not affected.\n\n**@clerk/express**\n```ts\napp.use(clerkMiddleware({ frontendApiProxy: { enabled: true } }));\n```\n\n**@clerk/hono**\n```ts\napp.use('*', clerkMiddleware({ frontendApiProxy: { enabled: true } }));\n```\n\n**@clerk/fastify**\n```ts\nfastify.register(clerkPlugin, { frontendApiProxy: { enabled: true } });\n```\n\n**@clerk/backend**\n```ts\nimport { clerkFrontendApiProxy } from '@clerk/backend/proxy';\n```\n\nA quick way to check across your entire project:\n\n```sh\ngrep -r \"frontendApiProxy\\|clerkFrontendApiProxy\" .\n```\n\nIf there are no matches, you are not using this feature.\n\n\n## Recommended actions\n\nClerk's internal logs show no evidence of users utilizing the built-in proxy with the impacted versions. Despite that, if you are on an impacted version and use the built-in proxy we recommend upgrading and rotating your Clerk Secret Key immediately.\n\n1. **Upgrade** to the patched version of `@clerk/backend` (and `@clerk/express`, `@clerk/hono`, etc.)\n2. **Rotate your Clerk Secret Key** after upgrading - if an attacker exploited this vulnerability, they may have captured your key. Rotate it in the [Clerk Dashboard](https://dashboard.clerk.com) under **API Keys**.  You should deploy your application with the updated key before revoking the existing key.\n3. **Audit access logs** for requests to your proxy endpoint (`/__clerk/` by default) containing double slashes in the path.\n\n\n\n## Credit\n\nDiscovered during an internal code audit.","status":"published","published":"2026-03-27T19:58:19Z","modified":"2026-04-06T16:44:06Z","cvss":[{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-918"],"updated_at":"2026-11-02T14:39:47.945242Z"}],"nvd":[{"id":"CVE-2026-34076","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.","status":"published","published":"2026-04-01T18:16:29.527Z","modified":"2026-10-26T22:10:00.163Z","cvss":[{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-918"],"updated_at":"2026-11-02T14:12:12.73929Z"}],"osv":[{"id":"CVE-2026-34076","title":"Clerk JavaScript: SSRF in the opt-in clerkFrontendApiProxy feature may leak secret keys to unintended host","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.","status":"published","published":"2026-04-01T16:59:21.828Z","modified":"2026-10-28T02:30:39.083444925Z","cvss":[{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-918"],"updated_at":"2026-11-02T15:45:02.247031Z"},{"id":"GHSA-gjxx-92w9-8v8f","title":"Clerk: SSRF in the opt-in clerkFrontendApiProxy feature may leak secret keys to unintended host","description":"## Summary\n\nThe `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.\n\n## Affected packages\n\nOnly applications that have opted into the `frontendApiProxy` feature are affected. This feature is not enabled by default. **Users of `@clerk/nextjs` are not affected** due to how the framework handles repeated `/` in request paths.\n\n| Package | Affected versions | Fixed version |\n|---|---|---|\n| `@clerk/backend` | `\u003e= 3.0.0, \u003c= 3.2.2` | `3.2.3` |\n| `@clerk/express` | `\u003e= 2.0.0, \u003c= 2.0.6` | `2.0.7` |\n| `@clerk/hono` | `\u003e= 0.1.0, \u003c= 0.1.4` | `0.1.5` |\n| `@clerk/fastify` | `\u003e= 3.1.0, \u003c= 3.1.4` | `3.1.5` |\n\nSearch your codebase for the `frontendApiProxy` option. If none of the patterns below appear in your code, you are not affected.\n\n**@clerk/express**\n```ts\napp.use(clerkMiddleware({ frontendApiProxy: { enabled: true } }));\n```\n\n**@clerk/hono**\n```ts\napp.use('*', clerkMiddleware({ frontendApiProxy: { enabled: true } }));\n```\n\n**@clerk/fastify**\n```ts\nfastify.register(clerkPlugin, { frontendApiProxy: { enabled: true } });\n```\n\n**@clerk/backend**\n```ts\nimport { clerkFrontendApiProxy } from '@clerk/backend/proxy';\n```\n\nA quick way to check across your entire project:\n\n```sh\ngrep -r \"frontendApiProxy\\|clerkFrontendApiProxy\" .\n```\n\nIf there are no matches, you are not using this feature.\n\n\n## Recommended actions\n\nClerk's internal logs show no evidence of users utilizing the built-in proxy with the impacted versions. Despite that, if you are on an impacted version and use the built-in proxy we recommend upgrading and rotating your Clerk Secret Key immediately.\n\n1. **Upgrade** to the patched version of `@clerk/backend` (and `@clerk/express`, `@clerk/hono`, etc.)\n2. **Rotate your Clerk Secret Key** after upgrading - if an attacker exploited this vulnerability, they may have captured your key. Rotate it in the [Clerk Dashboard](https://dashboard.clerk.com) under **API Keys**.  You should deploy your application with the updated key before revoking the existing key.\n3. **Audit access logs** for requests to your proxy endpoint (`/__clerk/` by default) containing double slashes in the path.\n\n\n\n## Credit\n\nDiscovered during an internal code audit.","status":"published","published":"2026-03-27T19:58:19Z","modified":"2026-04-06T17:04:07.972168Z","cvss":[{"version":"3.1","score":7.4,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-918"],"updated_at":"2026-11-02T15:46:47.822182Z"}]}}