CVE-2025-67647: SvelteKit Denial of Service and SSRF Vulnerability in Prerendering
Summary
CVE-2025-67647: SvelteKit is vulnerable to denial of service and possible SSRF when using prerendering. Affects @sveltejs/kit versions >= 2.19.0, < 2.49.5. Fixed in 2.49.5. How to fix ↓
Check if this vulnerability affects your application
Upload a manifest or SBOM and we'll show whether you're affected, plus every other risky package in the same scan.
No signup required · Results in about 60 seconds
Background
SvelteKit is a modern framework for building web applications using Svelte. It provides features like server-side rendering, static site generation, and a rich ecosystem of adapters for deployment. However, certain versions of SvelteKit are susceptible to vulnerabilities that can lead to denial of service (DoS) and server-side request forgery (SSRF) when prerendering routes.
Vulnerability Detail
Versions of SvelteKit from 2.19.0 onwards are vulnerable to denial of service (DoS) and server-side request forgery (SSRF) under specific conditions. The vulnerability arises when an application has at least one prerendered route and is using the adapter-node without a configured ORIGIN environment variable, while also lacking a reverse proxy that validates Host headers. The DoS can cause the server process to terminate unexpectedly, while the SSRF can allow unauthorized access to internal services. Additionally, there is a risk of cross-site scripting (XSS) via cache poisoning, where an attacker can manipulate a CDN to cache malicious responses.
How To Fix
Latest published version: 3.1.0 as of 23 Oct 2026
npm install @sveltejs/kit@3.1.0Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
2.49.5
This is the first release that contains the fix.
npm install @sveltejs/kit@2.49.5Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
If immediate patching is not possible, consider implementing a reverse proxy that validates Host headers to mitigate the SSRF risk. Additionally, ensure that the ORIGIN environment variable is configured correctly to limit exposure.
Conclusion
The vulnerability identified as CVE-2025-67647 poses significant risks to applications using SvelteKit, particularly when prerendering routes. It is crucial to update to the latest patched versions of the affected packages and consider implementing workarounds to protect against potential exploits.
See every vulnerability recorded for @sveltejs/kit →
FAQ
Versions from 2.19.0 onwards are affected, with specific conditions for DoS and SSRF vulnerabilities.
The CVSS score for this vulnerability is 8.4, indicating a high severity level.
You can use Vulert's playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
The potential impacts include denial of service, unauthorized access to internal services, and possible cross-site scripting via cache poisoning.
Yes, you can implement a reverse proxy that validates Host headers and ensure the ORIGIN environment variable is configured to mitigate the risks.
References
Related vulnerabilities
Recent vulnerabilities recorded for @sveltejs/kit.
