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

Quick assessment

Affected
Effect-TS effect
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Effect Monorepo是Effect开源的一个用于构建TypeScript应用的功能式框架。 Effect Monorepo 3.20.0之前版本存在竞争条件问题漏洞，该漏洞源于RpcServer.toWebHandler存在上下文混淆，可能导致读取其他并发请求的上下文。

CVSS 7.4 · High EPSS 0.27% · P18

Possible ATT&CK Techniques 1 AI

T1530 · Data from Cloud Storage
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I. Basic Information for CVE-2026-32887

Vulnerability Information
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Vulnerability Title
Effect Bug: `AsyncLocalStorage` context lost/contaminated inside Effect fibers under concurrent load with RPC
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用共享资源的并发执行不恰当同步问题(竞争条件)
Source: CVE Program / CVE List V5
Vulnerability Title
Effect Monorepo 竞争条件问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Effect Monorepo是Effect开源的一个用于构建TypeScript应用的功能式框架。 Effect Monorepo 3.20.0之前版本存在竞争条件问题漏洞，该漏洞源于RpcServer.toWebHandler存在上下文混淆，可能导致读取其他并发请求的上下文。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Effect-TS effect < 3.20.0 -

II. Public POCs for CVE-2026-32887

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III. Intelligence Information for CVE-2026-32887

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Vendor Advisories for CVE-2026-32887 (1)

IV. Related Vulnerabilities

Same product: effect
Same weakness: CWE-362

V. Comments for CVE-2026-32887

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