Threat Investigation
Request a demo

CVE-2026-27122

Medium

Description

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 contains unexpected characters, it can result in HTML injection in the SSR output. Client-side rendering is not affected. This vulnerability is fixed in 5.51.5.

SeverityMedium
CVSS5.4
Exploit probability—
ProductSvelte
PublishedFeb 20, 2026
First seenFeb 20, 2026
Weakness typeCWE-79Cross-site scripting (XSS)

How to fix

Update
  • svelte svelte5.51.5 or later
  • svelte5.51.5 or later

Affected products

ProductAffected versionsFixed in
svelte sveltev < 5.51.55.51.5
sveltenpmv < 5.51.55.51.5

Check your version

Choose the product and enter the version you run to see whether it falls in the affected range.

In the Intelligence 360 plan

Attack Surface Management

See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.