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

March 20, 2026

Symptom	Severity
`auth()` returns wrong user’s session	Critical — authentication bypass
`cookies()` / `headers()` from Next.js read wrong request	High — data leakage
OpenTelemetry trace context crosses requests	Medium — incorrect traces
Works locally, fails in production	Hard to diagnose — only manifests under concurrent load

References

github.com/Effect-TS/effect
github.com/Effect-TS/effect/security/advisories/GHSA-38f7-945m-qr2g
github.com/advisories/GHSA-38f7-945m-qr2g
nvd.nist.gov/vuln/detail/CVE-2026-32887

Code Behaviors & Features

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