GHSA-j62c-4x62-9r35 CVE-2025-67647

SvelteKit is vulnerable to denial of service and possible SSRF when using prerendering

Critical npm

Severity: 0.0 / 10; Critical · CVSS 4.0
Exploit chance (EPSS): 0.52%; Chance of exploitation in the next 30 days. Higher than 44.00% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-248 Uncaught Exception; CWE-400 Uncontrolled Resource Consumption; CWE-918 Server-Side Request Forgery (SSRF)
Fix: Available; 2 packages have a fixed version

Description

Summary

Versions of SvelteKit are vulnerable to a server side request forgery (SSRF) and denial of service (DoS) under certain conditions.

Details

Affected versions from 2.44.0 onwards are vulnerable to DoS if:

your app has at least one prerendered route (export const prerender = true)

Affected versions from 2.19.0 onwards are vulnerable to DoS and SSRF if:

your app has at least one prerendered route (export const prerender = true)
AND you are using adapter-node without a configured ORIGIN environment variable, and you are not using a reverse proxy that implements Host header validation

Impact

The DoS causes the running server process to end.

The SSRF allows access to internal services that can be reached without authentication when fetched from SvelteKit's server runtime.

It is also possible to obtain an SXSS via cache poisoning, by forcing a potential CDN to cache an XSS returned by the attacker's server (the latter being able to specify the cache-control of their choice).

Credits

Allam Rachid (zhero;)
Allam Yasser (inzo)
d-xuan (wednesday)

Affected versions

npm

Package	Vulnerable	Fixed in
@sveltejs/adapter-node	`>= 5.4.1, < 5.5.1`	`5.5.1`
@sveltejs/kit	`>= 2.19.0, < 2.49.5`	`2.49.5`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

@sveltejs/adapter-node npm → `5.5.1`

npm

npm install @sveltejs/adapter-node@5.5.1

yarn

yarn add @sveltejs/adapter-node@5.5.1

pnpm

pnpm add @sveltejs/adapter-node@5.5.1

@sveltejs/kit npm → `2.49.5`

npm

npm install @sveltejs/kit@2.49.5

yarn

yarn add @sveltejs/kit@2.49.5

pnpm

pnpm add @sveltejs/kit@2.49.5

Severity breakdown

CVSS 4.0 0.0

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:L/VA:H/SC:L/SI:L/SA:N

Attack vector: Network
Attack complexity: Low
Attack requirements: Present
Privileges required: None
User interaction: None
Confidentiality (vulnerable system): High
Integrity (vulnerable system): Low
Availability (vulnerable system): High
Confidentiality (subsequent systems): Low
Integrity (subsequent systems): Low
Availability (subsequent systems): None

CVSS 3.1 9.1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: High

Weakness

CWE-248: Uncaught Exception

An exception is thrown from a function, but it is not caught.

CWE-400: Uncontrolled Resource Consumption

The product does not properly control the allocation and maintenance of a limited resource.

How to prevent it

Architecture and Design: Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
Architecture and Design: Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution is simply difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
Architecture and Design: Ensure that protocols have specific limits of scale placed on them.
Implementation: Ensure that all failures in resource allocation place the system into a safe posture.

CWE-918: Server-Side Request Forgery (SSRF)

The 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.

References

Advisories

nvd.nist.gov/vuln/detail/CVE-2025-67647

Packages

github.com/sveltejs/kit

Timeline

Jan 15, 2026 Published
Jun 17, 2026 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-27mw-82g8-phjj SvelteKit : XSS via untrusted cache-control header in prerendered page	Low	Also affects @sveltejs/kit
GHSA-pfhg-q3qv-9q6r SvelteKit: URL redirection to untrusted site via enhanced form submission	Medium	Also affects @sveltejs/kit
GHSA-29g2-3rmr-qm68 SvelteKit: ReDoS (O(n^2)) in content negotiation — unauthenticated DoS via the Accept header	Medium	Also affects @sveltejs/kit
GHSA-866w-xmhq-wj7x SvelteKit: Prototype pollution in file input deletion path in remote-function forms	Medium	Also affects @sveltejs/kit
GHSA-wqjv-9729-c5q2 SvelteKit: Big remote form function payloads can cause Node process to crash	Medium	Also affects @sveltejs/kit
GHSA-hgv7-v322-mmgr @sveltejs/kit: `query.batch` cross-talk	Medium	Also affects @sveltejs/kit
GHSA-3f6h-2hrp-w5wx @sveltejs/kit: Unvalidated redirect in handle hook causes Denial-of-Service	High	Also affects @sveltejs/kit
GHSA-2crg-3p73-43xp @sveltejs/adapter-node has a BODY_SIZE_LIMIT bypass	High	Also affects @sveltejs/kit

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