Cross-site scripting via spread attributes in Svelte SSR_CVE-2026-42599

5.1 / 10

MEDIUM

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

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.

Basic Information

ID CVE-2026-42599

Source GitHub_M

Published Jun 9, 2026 at 16:22

Affected Product

Vendor sveltejs

Product svelte

Version < 5.55.7

Affected Versions sveltejs svelte < 5.55.7

CWE Classification

CWE-79

References

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    "published": "2026-06-09T16:22:46.987Z",
    "modified": "2026-06-09T16:22:46.987Z",
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