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Vulnerability record · CVE-2026-42570 · published 9 June 2026

CVE-2026-42570: Svelte devalue allocation without limits vulnerability

Svelte · Devalue

Svelte 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.

7.5 CVSS 3.1 High EPSS 0.72% · top 48.1% CWE-770 · Allocation without limits
7.5CVSS 3.1 base score
0.72%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
8References
24 Aug 2026Last modified by NVD

Description

Svelte 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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/sveltejs/devalue/commit/206ca6712fbc380a4571c59de9ab04b91110792d Patch
https://github.com/sveltejs/devalue/releases/tag/v5.8.1 ProductRelease Notes
https://github.com/sveltejs/devalue/security/advisories/GHSA-77vg-94rm-hx3p Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:37272
https://access.redhat.com/errata/RHSA-2026:57590
https://access.redhat.com/security/cve/CVE-2026-42570
https://bugzilla.redhat.com/show_bug.cgi?id=2487050
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42570.json

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-42570), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.