CVE-2023-29008: SvelteKit framework has Insufficient CSRF protection for CORS requests

Vulnerability summary

CVE-2023-29008 is a high (CVSS 8.8) Server-Side Request Forgery vulnerability in svelte sveltekit. EPSS estimates a 0.37% chance of exploitation in the next 30 days, higher than 31.2% of scored vulnerabilities.

Timeline

1. 06-04-2023
   PublishedVulnerability first disclosed.
2. 10-02-2025
   Last modifiedVulnerability information updated.

Description

The SvelteKit framework offers developers an option to create simple REST APIs. This is done by defining a `+server.js` file, containing endpoint handlers for different HTTP methods. SvelteKit provides out-of-the-box cross-site request forgery (CSRF) protection to its users. The protection is implemented at `kit/src/runtime/server/respond.js`. While the implementation does a sufficient job of mitigating common CSRF attacks, the protection can be bypassed in versions prior to 1.15.2 by simply specifying an upper-cased `Content-Type` header value. The browser will not send uppercase characters, but this check does not block all expected CORS requests. If abused, this issue will allow malicious requests to be submitted from third-party domains, which can allow execution of operations within the context of the victim's session, and in extreme scenarios can lead to unauthorized access to users’ accounts. This may lead to all POST operations requiring authentication being allowed in the following cases: If the target site sets `SameSite=None` on its auth cookie and the user visits a malicious site in a Chromium-based browser; if the target site doesn't set the `SameSite` attribute explicitly and the user visits a malicious site with Firefox/Safari with tracking protections turned off; and/or if the user is visiting a malicious site with a very outdated browser. SvelteKit 1.15.2 contains a patch for this issue. It is also recommended to explicitly set `SameSite` to a value other than `None` on authentication cookies especially if the upgrade cannot be done in a timely manner.

• CWE-918Server-Side Request ForgeryThe web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
• CWE-352Cross-Site Request ForgeryThe web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.