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Fencer Intel
medium 5.3

CVE-2026-128116 json

SvelteKit: Protocol-relative module import during server-side route resolution allows cross-origin script execution

published 16d ago modified yesterday also EUVD-2026-125727 , GHSA-rqp5-r3wg-vg35

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository sveltejs/kit. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 18%
public exploits
0
none known

Summary

SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte. Prior to versions 2.70.4 and 3.1.1, apps configured with router.resolution: 'server' could treat a pathname beginning with // as a protocol-relative module specifier during client-side navigation. A socially engineered link could therefore make server-side route resolution import and execute JavaScript from another origin in the user's browser. This issue is fixed in 2.70.4 and 3.1.1.

Patch / fix

  • npm @sveltejs/kit 2.70.4, 3.1.1

Is CVE-2026-128116 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

0.26% chance of exploitation in the next 30 days, higher than 18% of all scored CVEs (FIRST EPSS, 2026-11-14).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
npm @sveltejs/kit
<=2.70.3, >=3.0.0, <=3.1.0
2.70.4
3.1.1

Affected products

  • sveltejs kit

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

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.