Home/CVE/Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the
CVE

CVE-2026-30226

Svelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the

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.

HIGH · CVSS 7.5 EPSS 0.00143
Schedule remediation
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

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

Affected Products & Versions

1
svelte devalue< 5.6.4
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
npm devalue MODERATE fixed in 5.6.4
▣

Scoring & Timeline

7.5
HIGH · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD11 Mar 2026 · 06:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/sveltejs/devalue/security/advisories/GHSA-cfw5-2vxh-hr84Vendor Advisory
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