Medium, CVSS 5.3npmAmendedPublished
Vercel Workflow Allows Webhook Creation with Predictable User-Specified Tokens
GHSA-9r75-g2cr-3h76
- Affected
- npm workflow <= 4.1.0-beta.63
- Fixed in
- 4.2.0-beta.64· Vendor fix available
- Issue
- 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…
Recommended action: Upgrade to 4.2.0-beta.64 (pre-release) or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.