Svelte devalue: DoS via sparse array deserialization

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Summary

CVECVE-2026-42570
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-09 17:17:07 UTC
Updated2026-06-11 18:52:51 UTC
DescriptionSvelte devalue is a JavaScript library that serializes values into strings when JSON.stringify isn't sufficient for the job. From version 5.6.3 to before version 5.8.1, devalue.parse could, due to quirks in some JavaScript engines, be convinced to allocate much more memory than was needed when deserializing sparse arrays, leading to excessive memory consumption. This issue has been patched in version 5.8.1.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.003460000 probability, percentile 0.263190000 (date 2026-06-18)

Problem Types: CWE-770 | CWE-770 CWE-770: Allocation of Resources Without Limits or Throttling

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Svelte Devalue All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Sveltejs Devalue affected >= 5.6.3, < 5.8.1 Not specified

References

ReferenceSourceLinkTags
github.com/sveltejs/devalue/security/advisories/GHSA-77vg-94rm-hx3p [email protected] github.com Vendor Advisory
github.com/sveltejs/devalue/releases/tag/v5.8.1 [email protected] github.com Product, Release Notes
github.com/sveltejs/devalue/commit/206ca6712fbc380a4571c59de9ab04b91110792d [email protected] github.com Patch
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