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Medium · 6.5 CVE-2026-31865 EUVD-2026-12749GHSA-8hq9-phh3-p2wp

Elysia Cookie Value Prototype Pollution

Published Mar 18, 2026 · Updated Mar 18, 2026 · Assigned by GitHub_M

Description

Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation, and client-server communication. Prior to version 1.4.27, an Elysia cookie can be overridden by prototype pollution , eg. `__proto__`. This issue is patched in 1.4.27. As a workaround, use t.Cookie validation to enforce validation value and/or prevent iterable over cookie if possible.

Affected products

VendorProductAffectedFixed
elysiajs elysia < 1.4.27 —

Affected packages

EcosystemPackageAffectedFixedRecord
npm elysia < 1.4.27 1.4.27 GHSA-8hq9-phh3-p2wp

References