GHSA-9r75-g2cr-3h76 is a medium-severity (CVSS 5.3) vulnerability in workflow. A fix is available for workflow — see the affected versions and patch details below.
Vercel Workflow Allows Webhook Creation with Predictable User-Specified Tokens
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
workflownpm@workflow/corenpmDescription
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
tokenoption fromcreateWebhook()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()tocreateHook()instead and programmatically resume hooks usingresumeHook()instead of the public webhook endpoint, or - use
createWebhook()without passing a user-providedtoken, which uses a non-guessable randomnanoidby default.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | workflow | all versions | 4.2.0-beta.64npm install workflow@4.2.0-beta.64 |
| 📦npm | @workflow/core | all versions | 4.2.0-beta.64npm install @workflow/core@4.2.0-beta.64 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for workflow, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update workflow to 4.2.0-beta.64 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9r75-g2cr-3h76 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-9r75-g2cr-3h76 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-9r75-g2cr-3h76. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-9r75-g2cr-3h76 in your dependencies?
O3 Security finds GHSA-9r75-g2cr-3h76 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.