Vulnerability in Effectful Effect
CVE-2026-32887
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.
Vulnerability class: Race Condition
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.003 (17.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 17.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000
Affected products
- Effectful Effect
- Effect-Ts Effect — versions < 3.20.0
Weakness classification (CWE)
References
- github.com/Effect-TS/effect/security/advisories/GHSA-38f7-945m-qr2g (Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-32887?
- CVE-2026-32887 is a high-severity vulnerability in Effectful Effect, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 7.4/10. Published 2026-03-20.
- How severe is CVE-2026-32887?
- High severity. CVSS v3 base score is 7.4 out of 10.