medium5.3
CVE-2026-27902
Svelte: XSS via HTML Comment Injection in SSR Error Boundary Hydration Markers
Impact
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`.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | svelte | >= 5.53.0, < 5.53.5 | 5.53.5 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Svelte | Svelte | from 5.53.0 before 5.53.5 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/sveltejs/svelte/commit/0298e979371bb583855c9810db79a70a551d22b9
- https://github.com/sveltejs/svelte/releases/tag/svelte%405.53.5
- https://github.com/sveltejs/svelte/security/advisories/GHSA-qgvg-pr8v-6rr3
- https://github.com/advisories/GHSA-qgvg-pr8v-6rr3
- https://nvd.nist.gov/vuln/detail/CVE-2026-27902
- https://github.com/sveltejs/svelte/releases/tag/svelte@5.53.5