Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Svelte | Svelte | < 5.55.7 |
Related Weaknesses (CWE)
References
- https://github.com/sveltejs/svelte/releases/tag/svelte%405.55.7Release Notes
- https://github.com/sveltejs/svelte/security/advisories/GHSA-pr6f-5x2q-rwfpVendor Advisory
FAQ
What is CVE-2026-42599?
CVE-2026-42599 is a vulnerability with a CVSS score of 6.1 (MEDIUM). 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 o...
How severe is CVE-2026-42599?
CVE-2026-42599 has been rated MEDIUM with a CVSS base score of 6.1/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-42599?
Check the references section above for vendor advisories and patch information. Affected products include: Svelte Svelte.