MEDIUM

GHSA-qgvg-pr8v-6rr3

Svelte: XSS via HTML Comment Injection in SSR Error Boundary Hydration Markers

Quick fix

GHSA-qgvg-pr8v-6rr3 — svelte: upgrade to the fixed version with the command below.

npm install svelte@5.53.5

Details

Errors from `transformError` were not correctly escaped prior to being embedded in the HTML output, causing potential HTML injection and XSS if attacker-controlled content is returned from `transformError`.

Are you affected?

Enter the version of the package you're using.

Affected packages

npm/svelte

Introduced in: 5.53.0Fixed in: 5.53.5

Fixnpm install svelte@5.53.5

References

https://github.com/sveltejs/svelte/security/advisories/GHSA-qgvg-pr8v-6rr3[WEB]
https://nvd.nist.gov/vuln/detail/CVE-2026-27902[ADVISORY]
https://github.com/sveltejs/svelte/commit/0298e979371bb583855c9810db79a70a551d22b9[WEB]
https://github.com/sveltejs/svelte[PACKAGE]
https://github.com/sveltejs/svelte/releases/tag/svelte@5.53.5[WEB]