medium5.1
CVE-2026-27122
Svelte SSR does not validate dynamic element tag names in `<svelte:element>`
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | svelte | <= 5.51.4 | 5.51.5 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Svelte | Svelte | before 5.51.5 |