What is CVE-2026-30226?

CVE-2026-30226 is a high-severity vulnerability in Svelte Devalue, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 7.5/10. Published 2026-03-11.

How severe is CVE-2026-30226?

High severity. CVSS v3 base score is 7.5 out of 10.

Prototype Pollution in Svelte Devalue

CVE-2026-30226

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 mal…

Vulnerability class: Prototype Pollution

EPSS: 0.004 (29.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Svelte Devalue
Sveltejs Devalue — versions < 5.6.4

Weakness classification (CWE)

CWE-1321 — Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution)

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)

Frequently asked questions

What is CVE-2026-30226?: CVE-2026-30226 is a high-severity vulnerability in Svelte Devalue, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 7.5/10. Published 2026-03-11.
How severe is CVE-2026-30226?: High severity. CVSS v3 base score is 7.5 out of 10.