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.
History

Mon, 23 Feb 2026 21:00:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:svelte:svelte:*:*:*:*:*:node.js:*:*
Metrics cvssV3_1

{'score': 5.6, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L'}

cvssV3_1

{'score': 6.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N'}


Mon, 23 Feb 2026 15:00:00 +0000

Type Values Removed Values Added
First Time appeared Svelte
Svelte svelte
Vendors & Products Svelte
Svelte svelte

Sat, 21 Feb 2026 12:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.6, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L'}

threat_severity

Moderate


Fri, 20 Feb 2026 22:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Svelte SSR attribute spreading includes inherited properties from prototype chain
Weaknesses CWE-915
References
Metrics cvssV4_0

{'score': 5.3, 'vector': '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'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-02-20T22:29:45.364Z

Reserved: 2026-02-17T18:42:27.043Z

Link: CVE-2026-27125

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2026-02-20T23:16:02.780

Modified: 2026-02-23T20:52:23.960

Link: CVE-2026-27125

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-02-20T22:29:45Z

Links: CVE-2026-27125 - Bugzilla