MEDIUM
GHSA-crpf-4hrx-3jrp
Svelte SSR attribute spreading includes inherited properties from prototype chain
Quick fix
GHSA-crpf-4hrx-3jrp — svelte: upgrade to the fixed version with the command below.
npm install svelte@5.51.5Details
In server-side rendering, attribute spreading on elements (e.g. `<div {...attrs}>`) enumerates inherited properties from the object's prototype chain rather than only own properties. In environments where `Object.prototype` has already been polluted — a precondition outside of Svelte's control — this can cause unexpected attributes to appear in SSR output or cause SSR to throw errors. Client-side rendering is not affected.
Are you affected?
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Affected packages
References
- https://github.com/sveltejs/svelte/security/advisories/GHSA-crpf-4hrx-3jrp[WEB]
- https://nvd.nist.gov/vuln/detail/CVE-2026-27125[ADVISORY]
- https://github.com/sveltejs/svelte/commit/73098bb26c6f06e7fd1b0746d817d2c5ee90755f[WEB]
- https://github.com/sveltejs/svelte[PACKAGE]
- https://github.com/sveltejs/svelte/releases/tag/svelte@5.51.5[WEB]