CVE-2026-128123

5.9 MEDIUM Fix listed Denial of service Web app

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of service disruption.
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-11-12 22:42 UTC ReservedThe CVE id was reserved by its CNA
2026-11-13 20:18 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-11-13 22:14 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: not scored yet.
Severity: 5.9 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-11-13 20:18 UTC
Last modified: 2026-11-13 22:14 UTC
Weakness: CWE-248
Record status: Deferred

Attack profile CVSS 3.1 · 5.9

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Raw vector

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

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-128123.md and follow it. Check whether this project is affected by CVE-2026-128123. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record