GHSA-9r75-g2cr-3h76: Workflow Remote Code Execution Vulnerability

MODERATE
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CVSS 5.3
CWE-287
Published
Advisory Summary

GHSA-9r75-g2cr-3h76 is a MODERATE (CVSS 5.3) remote code execution vulnerability (CWE-287: Improper Authentication) affecting Workflow libraries in the npm ecosystem. The issue involves vercel workflow allows webhook creation with predictable user-specified tokens. Remediation is available by upgrading affected packages to version 4.2.0-beta.64.

GHSA-9r75-g2cr-3h76 at a Glance

CVE Identifier N/A
GHSA Identifier GHSA-9r75-g2cr-3h76
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-287: Improper Authentication
Affected Product Workflow
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity Low (I:L)
Availability None (A:N)

How to Fix GHSA-9r75-g2cr-3h76

To remediate this vulnerability, upgrade all affected Workflow dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

workflow fixed: 4.2.0-beta.64 
npm install workflow@4.2.0-beta.64
@workflow/core fixed: 4.2.0-beta.64 
npm install @workflow/core@4.2.0-beta.64
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls workflow

How to Check if You Are Affected

To determine whether your Node.js application is affected by GHSA-9r75-g2cr-3h76, inspect your project dependencies using npm:

npm ls workflow

Analyze the terminal output to locate any version of Workflow in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.2.0-beta.64), your application is affected.

Note: The npm ls workflow command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-287: Improper Authentication, where when an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. In Workflow, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

`createWebhook()` in Vercel Workflow DevKit accepts a user-specified `token` parameter that serves as the credential for the public webhook endpoint `/.well-known/workflow/v1/webhook/{token}`. Official documentation recommended predictable token patterns, making it possible for an unauthenticated remote attacker to guess the token and inject arbitrary payloads into the workflow execution context. #### Impact An attacker who guesses a webhook token can resume the associated workflow with an attacker-controlled HTTP request body, potentially triggering downstream side effects such as API calls, database writes, or deployments. #### Fix * Upgrade to version 4.2.0-beta.64. The fix removes the `token` option from `createWebhook()` so that webhook tokens are always randomly generated by the SDK. * Runs created with versions prior to 4.2.0-beta.64, that are 1) still active (i.e. running), and 2) have open hooks, are still susceptible to this vulnerability. If users suspect the hook tokens are predictable or leaked - consider cancelling those runs and restarting them on the latest patch. #### Workarounds In case a version upgrade is not possible, avoid passing predictable or guessable values to the `token` parameter of `createWebhook()`. Instead, users can either * switch from `createWebhook()` to `createHook()` instead and programmatically resume hooks using `resumeHook()` instead of the public webhook endpoint, or * use `createWebhook()` without passing a user-provided `token`, which uses a non-guessable random `nanoid` by default.

GHSA-9r75-g2cr-3h76 Affected Workflow Versions

2 component(s)
Fixed Versions:
4.2.0-beta.64
Product / Package Ecosystem Affected Versions Fixed Version
workflow
npm/workflow
npm
< 4.2.0-beta.64
4.2.0-beta.64
@workflow/core
npm/@workflow/core
npm
< 4.2.0-beta.64
4.2.0-beta.64

References

GitHub Advisory / Wiki ADVISORY
https://github.com/vercel/workflow/security/advisories/GHSA-9r75-g2cr-3h76
Security Fix Commit FIX COMMIT
https://github.com/vercel/workflow/commit/30e24d441e735635ffa4522198e6905d0e51e175
Workflow Source Repository REPOSITORY
https://github.com/vercel/workflow
Workflow Release RELEASE
https://github.com/vercel/workflow/releases/tag/workflow%404.2.0-beta.64

Frequently Asked Questions

What is GHSA-9r75-g2cr-3h76?
GHSA-9r75-g2cr-3h76 is a security vulnerability in Workflow involving Vercel Workflow Allows Webhook Creation with Predictable User-Specified Tokens under CWE-287: Improper Authentication.
Which Workflow versions are affected?
Affected versions include releases prior to 4.2.0-beta.64 across affected packages: workflow, @workflow/core.
What version fixes GHSA-9r75-g2cr-3h76?
Upgrading to 4.2.0-beta.64 (or the latest patched release for your respective branch) resolves the vulnerability.
Is workflow affected?
Yes, workflow is affected in releases prior to 4.2.0-beta.64. Upgrade your dependency to 4.2.0-beta.64 or later.
Is @workflow/core affected?
Yes, @workflow/core is affected in releases prior to 4.2.0-beta.64. Upgrade your dependency to 4.2.0-beta.64 or later.
What is the CVSS score of GHSA-9r75-g2cr-3h76?
GHSA-9r75-g2cr-3h76 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with GHSA-9r75-g2cr-3h76?
GHSA-9r75-g2cr-3h76 is classified under CWE-287: Improper Authentication (When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.).
How can I check npm dependencies for GHSA-9r75-g2cr-3h76?
Run the dependency tree command: 'npm ls workflow'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-9r75-g2cr-3h76",
  "modified" : "2026-03-06T18:45:02Z",
  "published" : "2026-03-06T18:45:02Z",
  "aliases" : [ ],
  "summary" : "Vercel Workflow Allows Webhook Creation with Predictable User-Specified Tokens",
  "details" : "`createWebhook()` in Vercel Workflow DevKit accepts a user-specified `token` parameter that serves as the credential for the public webhook endpoint `/.well-known/workflow/v1/webhook/{token}`. Official documentation recommended predictable token patterns, making it possible for an unauthenticated remote attacker to guess the token and inject arbitrary payloads into the workflow execution context.\n\n#### Impact\n\nAn attacker who guesses a webhook token can resume the associated workflow with an attacker-controlled HTTP request body, potentially triggering downstream side effects such as API calls, database writes, or deployments.\n\n#### Fix\n\n* Upgrade to version 4.2.0-beta.64. The fix removes the `token` option from `createWebhook()` so that webhook tokens are always randomly generated by the SDK.\n* Runs created with versions prior to 4.2.0-beta.64, that are 1) still active (i.e. running), and 2) have open hooks, are still susceptible to this vulnerability. If users suspect the hook tokens are predictable or leaked - consider cancelling those runs and restarting them on the latest patch.\n\n#### Workarounds\n\nIn case a version upgrade is not possible, avoid passing predictable or guessable values to the `token` parameter of `createWebhook()`. Instead, users can either\n\n* switch from `createWebhook()` to `createHook()` instead and programmatically resume hooks using `resumeHook()` instead of the public webhook endpoint, or\n* use `createWebhook()` without passing a user-provided `token`, which uses a non-guessable random `nanoid` by default.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "workflow"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.2.0-beta.64"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.0-beta.63"
    }
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@workflow/core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.2.0-beta.64"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.0-beta.63"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/vercel/workflow/security/advisories/GHSA-9r75-g2cr-3h76"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vercel/workflow/commit/30e24d441e735635ffa4522198e6905d0e51e175"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/vercel/workflow"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/vercel/workflow/releases/tag/workflow%404.2.0-beta.64"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-287" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-06T18:45:02Z",
    "nvd_published_at" : null
  }
}