svelte performance oriented web framework. Versions of svelte prior to 5.51.5 are vulnerable to cross-site scripting (XSS) during server-side rendering. When using spread syntax to render attributes from untrusted data, event handler properties are included in the rendered HTML output. If an application spreads user-controlled or external data as element attributes, an attacker can inject malicious event handlers that execute in victims' browsers. This vulnerability is fixed in 5.51.5.

Metrics

Attack Vector Network

Attack Complexity High

Privileges Required High

Attack Requirements Present

User Interaction None

Vulnerable System Confidentiality Impact Low

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact High

Subsequent System Integrity Impact High

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Scope Changed

Confidentiality Impact Low

Integrity Impact Low

Availability Impact None

User Interaction Required

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploitation none

Automatable no

Technical Impact partial

Affected Vendors & Products

Vendors Products
Svelte
  • Svelte

Configuration 1 [-]

cpe:2.3:a:svelte:svelte:*:*:*:*:*:node.js:*:*

No data.

References
Link Providers
https://www.spirityenterprise.com/pentest spirity
https://github.com/sveltejs/svelte/security/advisories/GHSA-f7gr-6p89-r883 cve-icon cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-27121 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-27121 cve-icon
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': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N'}

Mon, 23 Feb 2026 20:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

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. Versions of svelte prior to 5.51.5 are vulnerable to cross-site scripting (XSS) during server-side rendering. When using spread syntax to render attributes from untrusted data, event handler properties are included in the rendered HTML output. If an application spreads user-controlled or external data as element attributes, an attacker can inject malicious event handlers that execute in victims' browsers. This vulnerability is fixed in 5.51.5.
Title Svelte affected by cross-site scripting via spread attributes in Svelte SSR
Weaknesses CWE-79
References
Metrics cvssV4_0

{'score': 5.1, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N'}
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-02-23T19:34:18.150Z

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

Link: CVE-2026-27121

cve-icon Vulnrichment

Updated: 2026-02-23T19:33:25.737Z

cve-icon NVD

Status : Analyzed

Published: 2026-02-20T23:16:02.503

Modified: 2026-02-23T20:53:34.367

Link: CVE-2026-27121

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-02-20T22:27:36Z

Links: CVE-2026-27121 - Bugzilla