---
id: CVE-2025-66457
title: >-
  Elysia is a Typescript framework for request validation, type inference,
  OpenAPI documentation and client-server communication
summary: >-
  Elysia is a Typescript framework for request validation, type inference,
  OpenAPI documentation and client-server communication. Versions 1.4.17 and
  below are subject to arbitrary code execution from cookie config. When dynamic
  cookies ar…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-94
vendor: elysiajs
product: elysia
affected:
  - elysia < 1.4.18
patched:
  - elysia 1.4.18
published: '2025-12-09'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T21:10:00.183'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-66457'
references:
  - url: >-
      https://github.com/elysiajs/elysia/commit/26935bf76ebc43b4a43d48b173fc853de43bb51e
    label: security-advisories@github.com
  - url: >-
      https://github.com/elysiajs/elysia/commit/3af978663e437dccc6c1a2a3aff4b74e1574849e
    label: security-advisories@github.com
  - url: 'https://github.com/elysiajs/elysia/pull/1564'
    label: security-advisories@github.com
  - url: 'https://github.com/elysiajs/elysia/security/advisories/GHSA-8vch-m3f4-q8jf'
    label: security-advisories@github.com
  - url: 'https://github.com/elysiajs/elysia/security/advisories/GHSA-hxj9-33pp-j2cc'
    label: security-advisories@github.com
  - url: 'https://github.com/sportshead/elysia-poc'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
epss: 0.00807
epssPercentile: 0.5588
ingestedAt: '2026-10-14T21:57:04.770Z'
---

## Overview

Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation and client-server communication. Versions 1.4.17 and below are subject to arbitrary code execution from cookie config. When dynamic cookies are enabled (e.g. there  an existing cookie schema), the cookie config is injected into the compiled route without first being sanitised. Availability of this exploit is generally low, but when combined with GHSA-hxj9-33pp-j2cc, it allows for a full RCE chain. An attack requires write access to either the Elysia app's source code (in which case the vulnerability is meaningless) or write access to the cookie config (perhaps where it is assumed to be provisioned by the environment). This issue is fixed in version 1.4.18.

## Affected

- `elysia < 1.4.18`

## Remediation

Upgrade past the affected range:

- `elysia 1.4.18`