What is CVE-2026-27122?

CVE-2026-27122 is a medium-severity vulnerability in Svelte, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-02-20.

How severe is CVE-2026-27122?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Svelte

CVE-2026-27122

svelte performance oriented web framework. Prior to 5.51.5, when using <svelte:element this={tag}> in server-side rendering, the provided tag name is not validated or sanitized before being emitted into the HTML output. If the tag string c…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.002 (8.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

Affected products

Svelte
Sveltejs Svelte — versions < 5.51.5

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)

Frequently asked questions

What is CVE-2026-27122?: CVE-2026-27122 is a medium-severity vulnerability in Svelte, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-02-20.
How severe is CVE-2026-27122?: Medium severity. CVSS v3 base score is 5.4 out of 10.