Svelte: XSS via HTML Comment Injection in SSR Error Boundary Hydration Markers
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 software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | svelte | >= 5.53.0, < 5.53.5 | 5.53.5 |
References
- https://github.com/sveltejs/svelte/security/advisories/GHSA-qgvg-pr8v-6rr3
- https://nvd.nist.gov/vuln/detail/CVE-2026-27902
- https://github.com/sveltejs/svelte/commit/0298e979371bb583855c9810db79a70a551d22b9
- https://github.com/sveltejs/svelte
- https://github.com/sveltejs/svelte/releases/tag/svelte@5.53.5
- CVSS vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N- Weakness (CWE)
CWE-79- Platform
- npm
- Package
svelte- Disclosed
- 26.02.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-qgvg-pr8v-6rr3 - CC BY 4.0
Vulnerability history: svelte
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 14
- First → latest
- 07.2022 05.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 1
- Medium 13
Disclosures per year
- 2022: 1
- 2023: 0
- 2024: 1
- 2025: 0
- 2026: 12
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