CVE-2026-30226

devalue has prototype pollution in devalue.parse and devalue.unflatten

State: Published
Severity: 6.3 Medium
Published: Mar 11, 2026
Updated: Mar 12, 2026
Reserved: Mar 4, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
4.0	6.3 Medium	CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N	GitHub_M

Weaknesses

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

Affected Products

Product	Versions
devaluesveltejs	< 5.6.4Affected

References

https://github.com/sveltejs/devalue/security/advisories/GHSA-cfw5-2vxh-hr84

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.