Vulnerability-Lookup

CVE-2026-34076 (GCVE-0-2026-34076)

Vulnerability from cvelistv5 – Published: 2026-04-01 16:59 – Updated: 2026-04-01 18:00

Title

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

Summary

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

7.4 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-01 18:00 UTC

CWE

CWE-918 - Server-Side Request Forgery (SSRF)

Assigner

GitHub_M mitre root

References

1 reference

URL	Tags
https://github.com/clerk/javascript/security/advi…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version	CPE status
clerk	javascript	Affected: @clerk/hono >= 0.1.0, < 0.1.5 Affected: @clerk/express >= 2.0.0, < 2.0.7 Affected: @clerk/backend >= 3.0.0, < 3.2.3 Affected: @clerk/fastify >= 3.1.0, < 3.1.5	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-34076

Vulnerability from fkie_nvd - Published: 2026-04-01 18:16 - Updated: 2026-06-17 10:38

Severity

7.4 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Summary

References

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

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "javascript",
          "vendor": "clerk",
          "versions": [
            {
              "status": "affected",
              "version": "@clerk/hono \u003e= 0.1.0, \u003c 0.1.5"
            },
            {
              "status": "affected",
              "version": "@clerk/express \u003e= 2.0.0, \u003c 2.0.7"
            },
            {
              "status": "affected",
              "version": "@clerk/backend \u003e= 3.0.0, \u003c 3.2.3"
            },
            {
              "status": "affected",
              "version": "@clerk/fastify \u003e= 3.1.0, \u003c 3.1.5"
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    }
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      "lang": "en",
      "value": "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\u0027s 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."
    }
  ],
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  "lastModified": "2026-06-17T10:38:31.453",
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GHSA-GJXX-92W9-8V8F

Vulnerability from github – Published: 2026-03-27 19:58 – Updated: 2026-04-06 16:44

Summary

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

Details

Summary

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.

Affected packages

Only 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.

Package	Affected versions	Fixed version
`@clerk/backend`	`>= 3.0.0, <= 3.2.2`	`3.2.3`
`@clerk/express`	`>= 2.0.0, <= 2.0.6`	`2.0.7`
`@clerk/hono`	`>= 0.1.0, <= 0.1.4`	`0.1.5`
`@clerk/fastify`	`>= 3.1.0, <= 3.1.4`	`3.1.5`

Search your codebase for the frontendApiProxy option. If none of the patterns below appear in your code, you are not affected.

@clerk/express

app.use(clerkMiddleware({ frontendApiProxy: { enabled: true } }));

@clerk/hono

app.use('*', clerkMiddleware({ frontendApiProxy: { enabled: true } }));

@clerk/fastify

fastify.register(clerkPlugin, { frontendApiProxy: { enabled: true } });

@clerk/backend

import { clerkFrontendApiProxy } from '@clerk/backend/proxy';

A quick way to check across your entire project:

grep -r "frontendApiProxy\|clerkFrontendApiProxy" .

If there are no matches, you are not using this feature.

Recommended actions

Clerk'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.

Upgrade to the patched version of @clerk/backend (and @clerk/express, @clerk/hono, etc.)
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 under API Keys. You should deploy your application with the updated key before revoking the existing key.
Audit access logs for requests to your proxy endpoint (/__clerk/ by default) containing double slashes in the path.

Credit

Discovered during an internal code audit.

Severity

7.4 (High)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.2.2"
      },
      "package": {
        "ecosystem": "npm",
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              "introduced": "3.0.0"
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        }
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        "ecosystem": "npm",
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          "events": [
            {
              "introduced": "0.1.0"
            },
            {
              "fixed": "0.1.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.1.4"
      },
      "package": {
        "ecosystem": "npm",
        "name": "@clerk/fastify"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.1.0"
            },
            {
              "fixed": "3.1.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-34076"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-27T19:58:19Z",
    "nvd_published_at": "2026-04-01T18:16:29Z",
    "severity": "HIGH"
  },
  "details": "## 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\u0027s `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(\u0027*\u0027, 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 \u0027@clerk/backend/proxy\u0027;\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\u0027s 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.",
  "id": "GHSA-gjxx-92w9-8v8f",
  "modified": "2026-04-06T16:44:03Z",
  "published": "2026-03-27T19:58:19Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/clerk/javascript/security/advisories/GHSA-gjxx-92w9-8v8f"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34076"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/clerk/javascript"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Clerk: SSRF in the opt-in clerkFrontendApiProxy feature may leak secret keys to unintended host"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Action not permitted

CVE-2026-34076 (GCVE-0-2026-34076)

FKIE_CVE-2026-34076

GHSA-GJXX-92W9-8V8F

Summary

Affected packages

Recommended actions

Credit

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