CVE-2023-29008 SvelteKit framework has Insufficient CSRF protection for CORS requests
Attackers can bypass CSRF protection in SvelteKit by using uppercase Content-Type headers, allowing unauthorized actions in victim sessions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2023-29008?
CVE-2023-29008 is a high-severity vulnerability in sveltejs kit, published on 6 Apr 2023. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Which versions are affected by CVE-2023-29008?
2 open source packages ship an affected version, including @sveltejs/kit. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
@sveltejs/kit npm | All versions | 1.15.2 |
@sveltejs/kit npm | All versions | 1.15.2 |
Products include Svelte Sveltekit.
How do I fix CVE-2023-29008?
Upgrade @sveltejs/kit to 1.15.2 or later.
Is CVE-2023-29008 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-29008 exists.
Other vulnerabilities in sveltejs kit
- CVE-2023-29003 SvelteKit has Insufficient Cross-Site Request Forgery Protection
- CVE-2026-82259 SvelteKit 2.49.0 before 2.53.3 Denial of Service via form
- CVE-2026-82260 SvelteKit before 2.52.2 Memory Exhaustion via Remote Form Deserialization
- CVE-2026-82261 SvelteKit before 2.52.2 CPU Exhaustion via Remote Form Deserialization
- CVE-2026-82256 SvelteKit before 2.69.1 Denial of Service via Remote Form
Sources
Also known as GHSA-gv7g-x59x-wf8f.