CVE-2026-42047

EUVD-2026-28441 · Published May 5, 2026

Inngest TypeScript SDK exposes environment variables via serve() handler on unhandled 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) 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

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.
Rotate any secrets that were presence in environment variables (process.env) within affected environments including Inngest signing keys and event keys
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" and the ability to delete older deployments 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.

Technologies

Inngest Inngest

Weaknesses

CWE-497CWE-200

CVSS scores

v3.18.6CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

MITRE ATT&CK

Inferred

Where this vulnerability fits in an attack

ReconImpact

Initial Access Discovery

T1190Exploit Public-Facing Application T1614System Location Discovery

References

Potentially impacted assets

See if this affects your attack surface

Latest trending attack

Criticalyesterday

Google Brotli decoder - Remote Code Execution via compressed requests (Exploitation Check)

This control is the second step of the Patrowl response to CVE-2026-111497 (Node2Shell). It complements the first control of 22 October 2026, which focused on the Node.js runtime, and does not replace it. Why a second control CVE-2026-111497 is an out-of-bounds write in the Google Brotli decoder, the library that decompresses Brotli ("br") data. It was first published as a Node.js vulnerability, because Node.js bundles this decoder. Later publications showed that the flaw is in the library itself. Every product that embeds an affected version of the decoder is concerned, whatever its language or vendor. A public proof of concept demonstrates code execution. Any server that decompresses request bodies sent with "Content-Encoding: br" exposes the decoder to unauthenticated attackers. Known cases include Express 5 and NestJS 11 on Node.js, Koa and Fastify setups, Bun, Envoy and Istio with request decompression enabled, and any application or reverse proxy that decodes Brotli request bodies with an affected library. The flaw also works in the other direction. A malicious server can compromise an unpatched client that decodes a Brotli response, for example Node.js fetch(), Python clients (requests, httpx, aiohttp, Scrapy) with the Brotli or brotlicffi package, or libcurl builds with Brotli support. What this control checks Patrowl sends small, valid Brotli-compressed requests to each asset and observes whether the server decodes them. The check does not depend on the technology: it detects the behaviour, whatever the stack behind it. These requests are what any legitimate client could send. They never reach the vulnerable code path and cannot affect the availability of the service. How to read the result Potentially impacted means the asset decodes Brotli request bodies: the attack surface is exposed. It does not confirm that the asset is vulnerable. The version of the Brotli decoder in use is not visible from the outside. This check covers applications that parse request bodies on their root path. A Not impacted result does not rule out exposure on other routes, nor on the client side. Checking the versions on the servers remains the only exhaustive verification. Affected and fixed versions Google Brotli 1.0.3 to 1.2.0 are affected, fixed in 1.0.10, 1.1.1 and 1.2.1. Fixed releases of the main products embedding it: Node.js 22.23.4, 24.22.1 and 26.12.1 (end-of-life lines 20.x and older and 25.x receive no fix), Bun 1.4.4, Envoy 1.37.8, 1.38.6, 1.39.3 and 1.40.0, Istio 1.29.9, 1.30.6 and 1.31.2, Python Brotli 1.2.1 and brotlicffi 1.2.1.0. Products that link against the system library depend on the Brotli package of the Linux distribution. Recommendations Update every component that embeds the Brotli decoder (only real fix). Start with the assets flagged by this control. Restart the processes after the update. Rebuild containers, single-executable applications and appliances that bundle an affected runtime or library. Reduce the exposure until the update is deployed. Reject requests with "Content-Encoding: br" at the reverse proxy, load balancer or WAF, case-insensitively and including lists such as "gzip, br". On Envoy and Istio, disable request decompression for Brotli. Review outbound calls. List the features that fetch content from servers you do not control, and patch the services that host them first.