What’s Vulnerable › Vulnerabilities

CVE-2025-57820: Svelte devalue vulnerable to prototype pollution

• Severity: high (CVSS 7.9 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-08-26 · updated 2026-06-17
• Weakness: CWE-1321

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 products

• sveltejs devalue: before 5.3.2

References

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

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