Description
An SSR XSS exists in async hydration when attacker‑controlled keys are passed to hydratable. The key is embedded inside a <script> block without HTML‑safe escaping, allowing </script> to terminate the script and inject arbitrary JavaScript. This enables remote script execution in users' browsers, with potential for session theft and account compromise. This issue affects Svelte: from 5.46.0 before 5.46.3.
Metrics
CVSS 3.1 6.1/10
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NWeakness enumeration
Affected software
| Vendor | Product | Versions |
|---|---|---|
| Svelte | Svelte | >= 5.46.0, < 5.46.3 |
References
- https://fluidattacks.com/advisories/lydianExploit, Third Party Advisory
- https://fluidattacks.com/advisories/lydianExploit, Third Party Advisory
- https://fluidattacks.com/advisories/lydianExploit, Third Party Advisory
- https://fluidattacks.com/advisories/lydianExploit, Third Party Advisory
- https://github.com/sveltejs/svelte/security/advisories/GHSA-6738-r8g5-qwp3Third Party Advisory
Timeline
- Published
- Jan 15, 2026
- Last modified
- Jun 17, 2026
- NVD status
- Analyzed