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Fencer Intel
medium 5.9

CVE-2026-128123 json

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

published 16d ago modified yesterday also EUVD-2026-125768 , GHSA-rqw3-x7hx-mm3p

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 40%
public exploits
0
none known

Summary

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.

Patch / fix

  • npm @sveltejs/adapter-node 5.5.8, 6.0.1

Is CVE-2026-128123 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

0.46% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-14).

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm @sveltejs/adapter-node
>=5.5.7, <5.5.8
>=6.0.0-next.0, <6.0.1
5.5.8
6.0.1

Affected products

  • sveltejs kit
  • @sveltejs adapter-node

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of sveltejs/kit published their own advisory on GitHub. Reviewed sources take precedence over it.