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MEDIUM · 5.4

CVE-2026-27121

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 f...

Vulnerability 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.

CVSS Score

5.4

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE

Affected Products

VendorProductVersions
SvelteSvelte< 5.51.5

Related Weaknesses (CWE)

CWE-79

References

FAQ

What is CVE-2026-27121?

CVE-2026-27121 is a vulnerability with a CVSS score of 5.4 (MEDIUM). 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 f...

How severe is CVE-2026-27121?

CVE-2026-27121 has been rated MEDIUM with a CVSS base score of 5.4/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-27121?

Check the references section above for vendor advisories and patch information. Affected products include: Svelte Svelte.