CVE-2025-66456

Dec. 9, 2025, 9:16 p.m.

9.1
Critical

Description

Elysia is a Typescript framework for request validation, type inference, OpenAPI documentation and client-server communication. Versions 1.4.0 through 1.4.16 contain a prototype pollution vulnerability in `mergeDeep` after merging results of two standard schema validations with the same key. Due to the ordering of merging, there must be an any type that is set as a standalone guard, to allow for the `__proto__ prop` to be merged. When combined with GHSA-8vch-m3f4-q8jf this allows for a full RCE by an attacker. This issue is fixed in version 1.4.17. To workaround, remove the `__proto__ key` from body.

Product(s) Impacted

Vendor Product Versions
Elysia
  • Elysia
  • 1.4.0-1.4.16, 1.4.17

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-1321
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.

*CPE(s)

Affected systems and software identified for this CVE.

Type Vendor Product Version Update Edition Language Software Edition Target Software Target Hardware Other Information
a elysia elysia 1.4.0-1.4.16 / / / / / / /
a elysia elysia 1.4.17 / / / / / / /

References

https://github.com/elysiajs/elysia/commit/26935bf76ebc43b4a43d48b173fc853de43bb51e
https://github.com/elysiajs/elysia/commit/3af978663e437dccc6c1a2a3aff4b74e1574849e
https://github.com/elysiajs/elysia/pull/1564
https://github.com/elysiajs/elysia/security/advisories/GHSA-8vch-m3f4-q8jf
https://github.com/elysiajs/elysia/security/advisories/GHSA-hxj9-33pp-j2cc
https://github.com/elysiajs/elysia/security/advisories/GHSA-8vch-m3f4-q8jf
https://github.com/elysiajs/elysia/security/advisories/GHSA-hxj9-33pp-j2cc

Tags

security-advisories@github.com
CWE-1321
2025-12-09
CVE-2025-66456

CVSS Score

9.1 / 10

CVSS Data - 4.0

  • Attack Vector: NETWORK
  • Attack Complexity: LOW
  • Attack Requirements: PRESENT
  • Privileges Required: NONE
  • User Interaction: NONE
  • Scope:
  • Confidentiality Impact: HIGH
  • Integrity Impact: HIGH
  • Availability Impact: NONE
  • Exploit Maturity: NOT_DEFINED

    • CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

    View Vector String

Timeline

Published: Dec. 9, 2025, 8:15 p.m.
Last Modified: Dec. 9, 2025, 9:16 p.m.

Status : Received

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

security-advisories@github.com

*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.