How severe is GHSA-9r75-g2cr-3h76?

GHSA-9r75-g2cr-3h76 has a CVSS score of 5.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-9r75-g2cr-3h76?

GHSA-9r75-g2cr-3h76 affects the following packages: workflow (npm), @workflow/core (npm). Ecosystems affected: npm.

How do I fix GHSA-9r75-g2cr-3h76?

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.

How do I detect GHSA-9r75-g2cr-3h76 in my npm dependencies?

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.

How do I mitigate GHSA-9r75-g2cr-3h76 if there is no patch (or I can't update yet)?

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.

Is GHSA-9r75-g2cr-3h76 actively exploited in the wild?

No public exploit code has been indexed for GHSA-9r75-g2cr-3h76 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-9r75-g2cr-3h76 published, and has it been updated?

GHSA-9r75-g2cr-3h76 was published on March 6, 2026 and was last updated on March 6, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

MEDIUM severity

Vercel Workflow Allows Webhook Creation with Predictable User-Specified TokensGHSA-9r75-g2cr-3h76

MEDIUMFix: vercel/workflow@30e24d4

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.

Published

Mar 6, 2026

Updated

Mar 6, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Mar 6, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

2 pkgs affected

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.

33other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

workflownpm

2.5Mdownloads / week

@workflow/corenpm

2.6Mdownloads / week

Description

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.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`workflow`	all versions	4.2.0-beta.64`npm install workflow@4.2.0-beta.64`
📦npm	`@workflow/core`	all versions	4.2.0-beta.64`npm install @workflow/core@4.2.0-beta.64`

Detection & mitigation playbook

Open-source dependency

Detect
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.

Frequently Asked Questions

`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

O3 Security · Impact-Aware SCA

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