> CVE-2025-66456 [CRITICAL]

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PUBLISHED
2025-12-09 20:15
MODIFIED
2025-12-09 20:15
CVSS_SCORE V3
9.1
EPSS (Prob. Exploit)
0.56%
Top 54.1%
DATA SOURCES:
NVD 🔗 2025-12-09 CVE PROJECT 🔗 2026-01-19 CWE MITRE 🔗 2026-11-01 FIRST EPSS 🔗 2026-10-25 GITHUB 🔗 2026-10-28

> 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.

> AFFECTED_PRODUCTS

ℹ️ Aucun produit affecté n'a encore été publié par NVD pour cette CVE.

> CVSS V3 METRICS

CVSS_VECTOR
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

> MÉTRIQUES CVSS DÉTAILLÉES

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
Métrique Valeur Interprétation
AV (Vecteur d'Attaque)
Attack Vector
Network (N)
Exploit possible à distance via réseau (HTTP, API, etc.)
AC (Complexité d'Attaque)
Attack Complexity
Low (L)
Peu de conditions requises pour exploiter
PR (Privilèges Requis)
Privileges Required
None (N)
Aucune authentification requise
UI (Interaction Utilisateur)
User Interaction
None (N)
Aucune interaction utilisateur nécessaire
S (Périmètre)
Scope
Unchanged (U)
Impact reste dans le périmètre du composant compromis
C (Impact Confidentialité)
Confidentiality Impact
High (H)
Divulgation totale d'informations
I (Impact Intégrité)
Integrity Impact
High (H)
Modification totale des données possible
A (Impact Disponibilité)
Availability Impact
None (N)
Aucune interruption de service

> RÉSUMÉ DES IMPACTS

Confidentialité
High
Divulgation totale d'informations
Intégrité
High
Modification totale des données possible
Disponibilité
None
Aucune interruption de service

> WEAKNESSES

CWE-1321

> CWE DETAILED DESCRIPTIONS

CWE-1321: Improperly Controlled Modification of Object Prototype Attributes - 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.

> GITHUB SECURITY ADVISORY

GHSA-hxj9-33pp-j2cc CRITICAL

Elysia vulnerable to prototype pollution with multiple standalone schema validation

AFFECTED PACKAGES:
NPM / elysia
>= 1.4.0, < 1.4.17
Fixed in: 1.4.17

> HISTORIQUE DES MODIFICATIONS

Première apparition
09/12/2025 20:15
Source: NVD
📊 ENRICHISSEMENT 01/11/2026 06:58
CWE
Champ modifié: Description CWE
Ancienne valeur:
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 ini...
Nouvelle valeur:
CWE-1321: Improperly Controlled Modification of Object Prototype Attributes - The product receives input from an upstream component that specifies attributes that are to be initialized or updated in a...
📊 ENRICHISSEMENT 19/01/2026 17:38
CVEPROJECT
Champ modifié: CVE Project
Ancienne valeur:
Non
Nouvelle valeur:
Oui
📊 ENRICHISSEMENT 01/01/2026 06:01
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
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 ini...
Total des modifications: 3 Dernière mise à jour: 1 week ago

> REFERENCES

https://github.com/elysiajs/elysia/commit/26935bf76ebc43b4a43d48b173fc853de43bb5...
https://github.com/elysiajs/elysia/commit/3af978663e437dccc6c1a2a3aff4b74e157484...
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
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