CVE-2025-66457

8.8 HIGH
Published: December 09, 2025 Modified: December 17, 2025

Description

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://github.com/elysiajs/elysia/pull/1564
Source: security-advisories@github.com
Issue Tracking Patch
https://github.com/elysiajs/elysia/security/advisories/GHSA-8vch-m3f4-q8jf
Source: security-advisories@github.com
Exploit Patch Vendor Advisory
https://github.com/elysiajs/elysia/security/advisories/GHSA-hxj9-33pp-j2cc
Source: security-advisories@github.com
Not Applicable
https://github.com/sportshead/elysia-poc
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Exploit Third Party Advisory

6 reference(s) from NVD

Quick Stats

CVSS v3 Score
8.8 / 10.0
EPSS (Exploit Probability)
0.1%
18th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

elysiajs