CVE-2026-27125: Svelte

Medium severity, CVSS 6.8. EPSS: 0.5% chance of exploitation in the next 30 days.

svelte performance oriented web framework. Prior to 5.51.5, 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. This vulnerability is fixed in 5.51.5.

Affected products

• Svelte Svelte: before 5.51.5 (fixed in 5.51.5)

Published 2026-02-20. Last modified 2026-06-17.