Svelte is a performance oriented web framework. Prior to version 5.55.7, 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. Note that this vulnerability only triggers if the user's browser has JavaScript enabled but Svelte's hydration mechanism does not reach the vulnerable element before the event fires. This issue has been patched in version 5.55.7.
History

Thu, 11 Jun 2026 18:45:00 +0000

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

{'score': 4.2, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N'}

cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}


Thu, 11 Jun 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 4.2, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N'}

threat_severity

Moderate


Tue, 09 Jun 2026 20:15:00 +0000

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

Tue, 09 Jun 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

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


Tue, 09 Jun 2026 17:15:00 +0000

Type Values Removed Values Added
Description Svelte is a performance oriented web framework. Prior to version 5.55.7, 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. Note that this vulnerability only triggers if the user's browser has JavaScript enabled but Svelte's hydration mechanism does not reach the vulnerable element before the event fires. This issue has been patched in version 5.55.7.
Title 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:N/VI:N/VA:N/SC:H/SI:H/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-06-09T16:22:46.987Z

Updated: 2026-06-09T18:39:04.806Z

Reserved: 2026-04-29T00:31:15.725Z

Link: CVE-2026-42599

cve-icon Vulnrichment

Updated: 2026-06-09T18:28:34.131Z

cve-icon NVD

Status : Analyzed

Published: 2026-06-09T17:17:07.550

Modified: 2026-06-11T18:41:34.993

Link: CVE-2026-42599

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-06-09T16:22:46Z

Links: CVE-2026-42599 - Bugzilla