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Fencer Intel
medium 5.9

CVE-2026-128122 json

SvelteKit: Prerendered redirect paths can inject arbitrary rules into the `_redirects` file generated by `@sveltejs/adapter-cloudflare`

published 15d ago modified 14h ago also EUVD-2026-125767 , GHSA-5wg4-q3ww-283h

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
—
no EPSS score yet
public exploits
0
none known

Summary

SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte. From version 4.7.0 until versions 7.2.10 and 8.0.2, @sveltejs/adapter-cloudflare allowed an attacker-influenced link crawled during prerendering to place whitespace, control characters, wildcards, or placeholders into a prerendered redirect path. The adapter wrote those paths into the Cloudflare _redirects output without output-context validation, allowing a path to create unintended routing rules that could redirect or expose requests beyond the intended prerendered route. This issue is fixed in 7.2.10 and 8.0.2.

Patch / fix

  • npm @sveltejs/adapter-cloudflare 7.2.10, 8.0.2

Is CVE-2026-128122 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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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:H/I:N/A:N
GitHub 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
npm @sveltejs/adapter-cloudflare
>=4.7.0, <7.2.10
>=8.0.0-next.0, <8.0.2
7.2.10
8.0.2

Affected products

  • sveltejs kit

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation
  • CWE-93 Improper Neutralization of CRLF Sequences
  • CWE-116 Improper Encoding or Escaping of Output

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.