Vulnerability GHSA-mwv9-gp5h-frr4

Low Risk
LOW RISK
CVSS Score: 3.0
Score Range: < 4.0
Low severity vulnerabilities (CVSS < 4.0). Hygiene issues that can accumulate but pose lower immediate risk.
8 months ago
March 12, 2026 at 04:38 PM UTC
Sveltejs devalue's `devalue.parse` and `devalue.unflatten` emit objects with `__proto__` own properties
>=4.0.0 <5.6.4
>=4.0.0 <5.6.4

Summary

Sveltejs devalue's `devalue.parse` and `devalue.unflatten` emit objects with `__proto__` own properties

Details

In some circumstances, devalue.parse and devalue.unflatten could emit objects with __proto__ own properties. This in and of itself is not a security vulnerability (and is possible with, for example, JSON.parse as well), but it can result in prototype injection if downstream code handles it incorrectly:

const result = devalue.parse(/* input creating an object with a __proto__ property */);
const target = {};
Object.assign(target, result); // target's prototype is now polluted

Impacted packages

Timeline

Published
8 months ago
March 12, 2026 at 04:38 PM UTC
Fixed (5.6.4)
7 months ago
March 16, 2026 at 12:38 AM UTC
Last Modified
12 hours ago
November 08, 2026 at 10:56 AM UTC