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Servers and applications

CVE-2026-128122

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

Severity
Medium 5.9
Published
13 Nov 2026
Last changed
13 Nov 2026
Added to UpHeron
13 Nov 2026
Fixed in
7.2.10, 8.0.2
Weakness
Cross-site scripting (CWE-79)CRLF injection (CWE-93)Improper output encoding (CWE-116)
Attack
Over the network · Only under certain conditions · No login needed · No user action needed
Attacker can
Read data
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Sources
CVE Program

Description

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.

From the CVE Program.

Affected software

SoftwareAffected versions
SvelteKitServers and applications · cna:sveltejs|kit
  • From 4.7.0 before 7.2.10
  • From 8.0.0-next.0 before 8.0.2

References

  • CVE.org https://www.cve.org/CVERecord?id=CVE-2026-128122