CPU exhaustion in SvelteKit remote form deserialization (experimental only)

Exploitation

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

CVSS 4.0

6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-82261: 0.49% estimated exploitation activity in the next 30 days; percentile 42.42 (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.

Versions of @sveltejs/kit prior to 2.52.2 with remote functions enabled are vulnerable to CPU exhaustion. Malformed form data can cause the server to become unresponsive while processing a request, resulting in denial of service. Only applications using both experimental.remoteFunctions and form are vulnerable.

Published by the source

19 Feb 2026, 20:30 UTC

Last modified by the source

2 Sep 2026, 03:55 UTC

Source last checked

26 Oct 2026, 12:42 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-88qp-p4qg-rqm6

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-88qp-p4qg-rqm6

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# Patch Next advisory brief: CVE-2026-82261

Advisory: CPU exhaustion in SvelteKit remote form deserialization (experimental only)
IDs: CVE-2026-82261, GHSA-88qp-p4qg-rqm6
Record: https://patchnext.com/advisories/cve-2026-82261 (revision 3, source checked 26 Oct 2026, 12:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @sveltejs/kit 2.52.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @sveltejs/kit: affected >= 2.49.0, <= 2.52.1; fixed in 2.52.2

## 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-88qp-p4qg-rqm6 (OSV record GHSA-88qp-p4qg-rqm6 lists affected ranges: npm @sveltejs/kit >=2.49.0 <2.52.2 (fixed))
- Verified: https://github.com/advisories/GHSA-88qp-p4qg-rqm6 (GitHub-reviewed advisory GHSA-88qp-p4qg-rqm6 lists affected ranges: npm @sveltejs/kit >=2.49.0 <=2.52.1)

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