Resource exhaustion in Svelte Devalue
CVE-2026-42570
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.007 (51.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 51.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.007 · change: +0.003
Affected products
- Svelte Devalue
- Sveltejs Devalue — versions >= 5.6.3, < 5.8.1
Weakness classification (CWE)
References
- github.com/sveltejs/devalue/commit/206ca6712fbc380a4571c59de9ab04b91110792d (Patch)
- github.com/sveltejs/devalue/releases/tag/v5.8.1 (Product, Release Notes)
- github.com/sveltejs/devalue/security/advisories/GHSA-77vg-94rm-hx3p (Vendor Advisory)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-42570?
- CVE-2026-42570 is a high-severity vulnerability in Svelte Devalue, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-06-09.
- How severe is CVE-2026-42570?
- High severity. CVSS v3 base score is 7.5 out of 10.