SvelteKit vulnerable to Cross-Site Request Forgery

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2023-29003: 0.56% estimated exploitation activity in the next 30 days; percentile 46.48 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary 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 it’s users. The protection is implemented at kit/src/runtime/server/respond.js#L52. While the implementation does a sufficient job in mitigating common CSRF attacks, the protection can be bypassed by simply specifying a different Content-Type header value. Details The CSRF protection is implemented using the code shown below. If the incoming request specifies a POST method (1), the protection will compare the server’s origin with the value of the HTTP Origin header (2). A mismatch between these values signals that a potential attack has been detected. The final check is performed on the request’s Content-Type header (3) whether the value is either application/x-www-form-urlencoded or multipart/form-data…

Published by the source

4 Apr 2023, 21:20 UTC

Last modified by the source

18 Oct 2026, 14:58 UTC

Source last checked

26 Oct 2026, 13:07 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-5p75-vc5g-8rv2

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-5p75-vc5g-8rv2

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# Patch Next advisory brief: CVE-2023-29003

Advisory: SvelteKit vulnerable to Cross-Site Request Forgery
IDs: CVE-2023-29003, GHSA-5p75-vc5g-8rv2
Record: https://patchnext.com/advisories/cve-2023-29003 (revision 2, source checked 26 Oct 2026, 13:07 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @sveltejs/kit 1.15.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @sveltejs/kit: affected < 1.15.1; fixed in 1.15.1

## Suggested inspection (read-only)
- `npm ls @sveltejs/kit --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @sveltejs/kit.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-5p75-vc5g-8rv2 (OSV record GHSA-5p75-vc5g-8rv2 lists affected ranges: npm @sveltejs/kit >=0 <1.15.1 (fixed))
- Verified: https://github.com/advisories/GHSA-5p75-vc5g-8rv2 (GitHub-reviewed advisory GHSA-5p75-vc5g-8rv2 lists affected ranges: npm @sveltejs/kit >=0 <1.15.1)

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