Medium (5.3) in svelte svelte. EPSS 0.3% chance of exploitation in the next 30 days. Fixed in svelte 5.46.4.
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.