CVE-2026-22803 SvelteKit has a memory amplification DoS in Remote Functions binary form deserializer
Attackers can cause server memory exhaustion and denial of service via crafted payloads in experimental remote functions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-22803?
CVE-2026-22803 is a high-severity denial of service vulnerability in sveltejs kit, published on 15 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte. From 2.49.0 to 2.49.4, the experimental form remote function uses a binary data format containing a representation of submitted form data. A specially-crafted payload can cause the server to allocate a large amount of memory, causing DoS via memory exhaustion. This vulnerability is fixed in 2.49.5.
Which versions are affected by CVE-2026-22803?
2 open source packages ship an affected version, including @sveltejs/kit. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
@sveltejs/kit npm | From 2.49.0 | 2.49.5 |
@sveltejs/kit npm | From 2.49.0 | 2.49.5 |
Products include Svelte Kit.
How do I fix CVE-2026-22803?
Upgrade @sveltejs/kit to 2.49.5 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-22803 being exploited?
There is no known exploitation of CVE-2026-22803 in the wild and no public exploit code.
Other vulnerabilities in sveltejs kit
Sources
Also known as GHSA-j2f3-wq62-6q46.