CVE-2026-30226: Svelte Devalue

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. In devalue v5.6.3 and earlier, devalue.parse and devalue.unflatten were susceptible to prototype pollution via maliciously crafted payloads. Successful exploitation could lead to Denial of Service (DoS) or type confusion. This vulnerability is fixed in 5.6.4.

Affected products

• Svelte Devalue: before 5.6.4 (fixed in 5.6.4)

Published 2026-03-11. Last modified 2026-06-17.