CVE-2026-32887

Effect Bug: `AsyncLocalStorage` context lost/contaminated inside Effect fibers under concurrent load with RPC

Effect is a TypeScript framework that consists of several packages that work together to help build TypeScript applications. Prior to version 3.20.0, when using `RpcServer.toWebHandler` (or `HttpApp.toWebHandlerRuntime`) inside a Next.js App Router route handler, any Node.js `AsyncLocalStorage`-dependent API called from within an Effect fiber can read another concurrent request's context — or no context at all. Under production traffic, `auth()` from `@clerk/nextjs/server` returns a different user's session. Version 3.20.0 contains a fix for the issue.

Affected

Effect-TS · effect

CVSS v3.1 GITHUB

7.4 HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS

0.28% chance of exploitation in the next 30 days, 20th percentile

Published

2026-03-20

Updated

2026-03-25

Proof-of-concept exploits (1)

• advisories/GHSA-38f7-945m-qr2g

Security advisories

• Effect-TS/effect/security/advisories/GHSA-38f7-945m-qr2g

References

• CVE Record
• NVD entry