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CVE-2026-128123

SvelteKit: `@sveltejs/adapter-node` crashes when proxying certain requests via `fetch`

  • Medium 5.9

Description

SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte. From version 5.5.7 until versions 5.5.8 and 6.0.1, , @sveltejs/adapter-node can attempt to add a header to an immutable request in a context that causes the server to crash, denying service to any other requests routed to that server. This issue is fixed in 5.5.8 and 6.0.1.

Key facts

Published
13 Nov 2026
Last changed
13 Nov 2026
Assigned by
GitHub_M
EPSS
0.461% likely to be exploited in the next 30 days, higher than 40.48% of CVEs (scores for 15 Nov 2026)

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

  • 5.9CVSS 3.1, Mediumfrom the CNA (GitHub_M)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.

No explicit remediation statement is available on this page yet. Consult the original record and vendor references before choosing a fix.

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

VendorProductVersions
sveltejskit
  • >= 3.0.0-next.0, < 3.1.1 (affected)
  • < 2.70.4 (affected)
@sveltejsadapter-node
  • >= 5.5.7, < 5.5.8 (affected)
  • >= 6.0.0-next.0, < 6.0.1 (affected)

Timeline

  1. 13 Nov 2026 Published

Weakness

References