CVE-2026-27125

EPSS 0.03%

Svelte SSR attribute spreading includes inherited properties from prototype chain

Published: 2/19/2026Modified: 4/4/2026

Also known as:GHSA-crpf-4hrx-3jrpCGA-fcqr-r83p-q47h

Description

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.

Affected packages (1)

npm/sveltefrom 0, < 5.51.5

CVSS scores

Source	Version	Severity	Vector
osv	CVSS 4.0	—	CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:H/SI:H/SA:N

References (5)

ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2026-27125
PATCHhttps://github.com/sveltejs/svelte
WEBhttps://github.com/sveltejs/svelte/commit/73098bb26c6f06e7fd1b0746d817d2c5ee90755f
WEBhttps://github.com/sveltejs/svelte/releases/tag/[email protected]
WEBhttps://github.com/sveltejs/svelte/security/advisories/GHSA-crpf-4hrx-3jrp