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.
References
https://fluidattacks.com/advisories/lydian
https://fluidattacks.com/advisories/lydian
https://github.com/sveltejs/svelte/security/advisories/GHSA-6738-r8g5-qwp3
CVSS impact metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.1 · Medium
Information
Source identifier
Vulnerability status
Analyzed
Published
2026-01-15T20:16:03.490Z
1 month agoLast modified
2026-01-23T19:04:53.167Z
3 weeks ago