CVE-2026-42599

Cross-site scripting via spread attributes in Svelte SSR

Published Jun 9, 2026 CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-pr6f-5x2q-rwfp Svelte SSR vulnerable to cross-site scripting via spread attributes
History
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'}

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

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

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

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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jun 9, 2026, 6:39 PM
Reserved
Apr 29, 2026, 12:31 AM
Status
Analyzed
Published
Jun 9, 2026, 5:17 PM
Modified
Jul 23, 2026, 8:10 AM
Severity
Moderate
Public date
Jun 9, 2026, 4:22 PM