CVE-2026-42047

Inngest is a platform for running event-driven and scheduled background functions with queueing, retries, and step orchestration. Versions 3.22.0 through 3.53.1 contain a vulnerability that allows unauthenticated remote attackers to exfiltrate environment variables from the host process via the serve() HTTP handler. The serve() handler implements GET, POST, and PUT methods. Requests using PATCH, OPTIONS, or DELETE fall through to a generic handler that returns diagnostic information. A change introduced in v3.22.0 caused this diagnostic response to include the contents of process.env, exposing any secrets, API keys, or credentials present in the environment. An application is vulnerable if its serve() endpoint is reachable via PATCH, OPTIONS, or DELETE requests, which is common in setups like Next.js Pages Router or Express's app.use(...). Not affected are Next.js App Router handlers that export only GET, POST, and PUT, and applications using the connect worker method. This issue has been fixed in version 3.54.0. To work around this issue if upgrading is not immediately possible, restrict the serve() endpoint at the framework or reverse-proxy layer to accept only GET, POST, and PUT. The Inngest serve() endpoint does not require any other HTTP methods.

Inngest is a platform for running event-driven and scheduled background functions with queueing, retries, and step orchestration. Versions 3.22.0 through 3.53.1 contain a vulnerability that allows unauthenticated remote attackers to exfiltrate environment variables from the host process via the serve() HTTP handler. The serve() handler implements GET, POST, and PUT methods. Requests using PATCH, OPTIONS, or DELETE fall through to a generic handler that returns diagnostic information. A change introduced in v3.22.0 caused this diagnostic response to include the contents of process.env, exposing any secrets, API keys, or credentials present in the environment. An application is vulnerable if its serve() endpoint is reachable via PATCH, OPTIONS, or DELETE requests, which is common in setups like Next.js Pages Router or Express's app.use(...). Not affected are Next.js App Router handlers that export only GET, POST, and PUT, and applications using the connect worker method. This issue has been fixed in version 3.54.0. To work around this issue if upgrading is not immediately possible, restrict the serve() endpoint at the framework or reverse-proxy layer to accept only GET, POST, and PUT. The Inngest serve() endpoint does not require any other HTTP methods.

# Summary A vulnerability in the Inngest TypeScript SDK versions `3.22.0` through `3.53.1` allows unauthenticated remote attackers to exfiltrate environment variables from the host process via the `serve()` HTTP handler. The `serve()` handler implements `GET`, `POST`, and `PUT` methods. Requests using `PATCH`, `OPTIONS`, or `DELETE` fall through to a generic handler that returns diagnostic information. A change introduced in `v3.22.0` caused this diagnostic response to include the contents of `process.env`, exposing any secrets, API keys, or credentials present in the environment. # Who is affected An application is vulnerable if **all** of the following are true: - It uses `inngest` SDK version `>= 3.22.0, <= 3.53.1` (inclusive) - Its `serve()` endpoint is reachable via `PATCH`, `OPTIONS`, or `DELETE` requests. Please check your framework's implementation for the serve handler ([documentation](https://www.inngest.com/docs/learn/serving-inngest-functions)) to asses whether it handles these HTTP methods. Common vulnerable configurations include: - Next.js Pages Router, which forwards all HTTP methods to the handler. - Express via `app.use('/api/inngest', serve(...))`, which routes `PATCH` and `OPTIONS` to the handler by default. The following are **not** affected: - Next.js App Router handlers that explicitly export only `GET`, `POST`, and `PUT`. - Applications using the `connect` worker method. - SDK versions `< 3.22.0` and `>= 3.54.0`, including all `4.x` releases. The vulnerability was responsibly disclosed by an Inngest user. At this time, there are no known reports of exploitation. # Remediation 1. Upgrade to `inngest@3.54.0` or later. The fix is backwards compatible with the `3.x` release line. The `4.x` line is also unaffected. 2. Rotate any secrets that were presence in environment variables (`process.env`) within affected environments including Inngest signing keys and event keys 3. Search logs for any requests to your `serve` endpoints using the `PATCH`, `OPTIONS`, `DELETE` http methods to assess if any environment variables may have been exposed. ## Additional recommendations Users on platforms with long-lived deployments (e.g. Vercel, Cloudflare Workers) should be aware that prior deployments remain reachable at their immutable URLs and may continue to expose the vulnerability even after a new deployment is promoted. For example, Vercel offers security features such as "[Deployment Protection](https://vercel.com/docs/deployment-protection#standard-protection)" and [the ability to delete older deployments](https://vercel.com/kb/guide/how-do-i-delete-an-individual-deployment) which can help immediately mitigate impact. For additional security, users can also adjust firewall or proxy rules to only allow requests to their `serve` endpoint from Inngest IP addresses available here: http://inngest.com/ips-v4, http://inngest.com/ips-v6 ### Workarounds If upgrading is not immediately possible, restrict the `serve()` endpoint at the framework or reverse-proxy layer to accept only `GET`, `POST`, and `PUT`. The Inngest `serve()` endpoint does not require any other HTTP methods. ### Resources - Rotating Inngest keys: https://www.inngest.com/docs/platform/manage/rotating-keys - Inngest signing keys: https://www.inngest.com/docs/platform/signing-keys - Inngest event keys: https://www.inngest.com/docs/events/creating-an-event-key - Inngest security best practices: https://www.inngest.com/docs/learn/security ### Credits - Ben Hylak - an independent security researcher, discovered and responsibly disclosed the vulnerability.

# Summary A vulnerability in the Inngest TypeScript SDK versions `3.22.0` through `3.53.1` allows unauthenticated remote attackers to exfiltrate environment variables from the host process via the `serve()` HTTP handler. The `serve()` handler implements `GET`, `POST`, and `PUT` methods. Requests using `PATCH`, `OPTIONS`, or `DELETE` fall through to a generic handler that returns diagnostic information. A change introduced in `v3.22.0` caused this diagnostic response to include the contents of `process.env`, exposing any secrets, API keys, or credentials present in the environment. # Who is affected An application is vulnerable if **all** of the following are true: - It uses `inngest` SDK version `>= 3.22.0, <= 3.53.1` (inclusive) - Its `serve()` endpoint is reachable via `PATCH`, `OPTIONS`, or `DELETE` requests. Please check your framework's implementation for the serve handler ([documentation](https://www.inngest.com/docs/learn/serving-inngest-functions)) to asses whether it handles these HTTP methods. Common vulnerable configurations include: - Next.js Pages Router, which forwards all HTTP methods to the handler. - Express via `app.use('/api/inngest', serve(...))`, which routes `PATCH` and `OPTIONS` to the handler by default. The following are **not** affected: - Next.js App Router handlers that explicitly export only `GET`, `POST`, and `PUT`. - Applications using the `connect` worker method. - SDK versions `< 3.22.0` and `>= 3.54.0`, including all `4.x` releases. The vulnerability was responsibly disclosed by an Inngest user. At this time, there are no known reports of exploitation. # Remediation 1. Upgrade to `inngest@3.54.0` or later. The fix is backwards compatible with the `3.x` release line. The `4.x` line is also unaffected. 2. Rotate any secrets that were presence in environment variables (`process.env`) within affected environments including Inngest signing keys and event keys 3. Search logs for any requests to your `serve` endpoints using the `PATCH`, `OPTIONS`, `DELETE` http methods to assess if any environment variables may have been exposed. ## Additional recommendations Users on platforms with long-lived deployments (e.g. Vercel, Cloudflare Workers) should be aware that prior deployments remain reachable at their immutable URLs and may continue to expose the vulnerability even after a new deployment is promoted. For example, Vercel offers security features such as "[Deployment Protection](https://vercel.com/docs/deployment-protection#standard-protection)" and [the ability to delete older deployments](https://vercel.com/kb/guide/how-do-i-delete-an-individual-deployment) which can help immediately mitigate impact. For additional security, users can also adjust firewall or proxy rules to only allow requests to their `serve` endpoint from Inngest IP addresses available here: http://inngest.com/ips-v4, http://inngest.com/ips-v6 ### Workarounds If upgrading is not immediately possible, restrict the `serve()` endpoint at the framework or reverse-proxy layer to accept only `GET`, `POST`, and `PUT`. The Inngest `serve()` endpoint does not require any other HTTP methods. ### Resources - Rotating Inngest keys: https://www.inngest.com/docs/platform/manage/rotating-keys - Inngest signing keys: https://www.inngest.com/docs/platform/signing-keys - Inngest event keys: https://www.inngest.com/docs/events/creating-an-event-key - Inngest security best practices: https://www.inngest.com/docs/learn/security ### Credits - Ben Hylak - an independent security researcher, discovered and responsibly disclosed the vulnerability.