Vulnerability · Published Aug 26, 2025 · Assigned by GitHub_M

CVE-2025-57820Svelte devalue vulnerable to prototype pollution

High 7.9

In plain English

A high-severity prototype pollution in devalue from sveltejs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)7.9High

Exploit odds (30 days)0.4%top 69.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Svelte devalue is a utility library. Prior to version 5.3.2, a string passed to devalue.parse could represent an object with a __proto__ property and devalue.parse does not check that an index is numeric. This could result in assigning prototypes to objects and properties, leading to prototype pollution. This issue has been fixed in version 5.3.2

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	devalue	5.3.2	GHSA-vj54-72f3-p5jv

Affected products (as reported)

Vendor	Product	Versions
sveltejs	devalue	< 5.3.2

Weakness: CWE-1321 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H

References

https://github.com/sveltejs/devalue/security/advisories/GHSA-vj54-72f3-p5jv x_refsource_CONFIRM
https://github.com/sveltejs/devalue/commit/0623a47c9555b639c03ff1baea82951b2d9d1132 x_refsource_MISC