Svelte vulnerable to XSS when using objects during server-side rendering

Description

The package svelte before 3.49.0 is vulnerable to Cross-site Scripting (XSS) due to improper input sanitization and to improper escape of attributes when using objects during SSR (Server-Side Rendering). Exploiting this vulnerability is possible via objects with a custom toString() function.

Recommendation

Update the svelte package to the latest compatible version. Followings are version details:

• Affected version(s): < 3.49.0
• Patched version(s): 3.49.0

References

• GHSA-wv8q-r932-8hc7
• snyk.io
• CVE-2022-25875
• CWE-79
• CAPEC-310
• OWASP 2021-A3
• OWASP 2021-A6

Related Issues

• svelte vulnerable to Cross-site Scripting - CVE-2025-15265
• tRPC has possible prototype pollution in `experimental_nextAppDirCaller` - CVE-2025-68130
• x402 SDK vulnerable in outdated versions in resource servers for builders - Vulnerability
• tarteaucitron.js vulnerable to DOM Clobbering via document.currentScript - CVE-2025-48939

Tags:

npm

svelte