CVE-2026-32887 HIGH

CVE-2026-32887: Effect Bug: `AsyncLocalStorage` context lost/contaminated inside Effect fibers under concurrent load with RPC

Vendor Effect-Ts
Product effect
Weakness CWE-362
Published March 20, 2026
Last update March 25, 2026
View on NVD All CVEs

CVSS base score

7.4/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

March 20, 2026 CVE published
March 25, 2026 Record updated