CVE-2026-42570
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.40%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.40% probability · 33th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-770
- Affected
- svelte/devalue
- Source
- security-advisories@github.com
References
- https://github.com/sveltejs/devalue/commit/206ca6712fbc380a4571c59de9ab04b91110792dPatch
- https://github.com/sveltejs/devalue/releases/tag/v5.8.1Product, Release Notes
- https://github.com/sveltejs/devalue/security/advisories/GHSA-77vg-94rm-hx3pVendor 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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.