CVE-2026-42570: Svelte devalue: DoS via sparse array deserialization

May 14, 2026 (updated June 9, 2026)

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.

References

github.com/advisories/GHSA-77vg-94rm-hx3p
github.com/sveltejs/devalue/commit/206ca6712fbc380a4571c59de9ab04b91110792d
github.com/sveltejs/devalue/releases/tag/v5.8.1
github.com/sveltejs/devalue/security/advisories/GHSA-77vg-94rm-hx3p
nvd.nist.gov/vuln/detail/CVE-2026-42570

Code Behaviors & Features

Detect and mitigate CVE-2026-42570 with GitLab Dependency Scanning

Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Learn more about Dependency Scanning →