# CVE-2026-40074: @sveltejs/kit DoS — Fixed in 2.57.1

📦 npm

Not in CISA KEV

# CVE-2026-40074 — @sveltejs/kit

[Fix: sveltejs/kit@10d7b44](https://github.com/sveltejs/kit/commit/10d7b44425c3d9da642eecce373d0c6ef83b4fcd)

CVE-2026-40074 is a CWE-755 vulnerability in @sveltejs/kit. A fix is available for @sveltejs/kit — see the affected versions and patch details below.

SvelteKit's invalidated redirect in handle hook causes Denial-of-Service

Also known as[GHSA-3f6h-2hrp-w5wx](/vulnerability/GHSA-3f6h-2hrp-w5wx)

Published

Apr 10, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

## Exploitation Status

### No confirmed exploitation observed yet

-   CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
-   CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-40074.

## EPSS Exploitation Probability

[via FIRST.org ↗](https://www.first.org/epss/)

0.4%probability of exploitation in next 30 days

Lower Risk+0.01%

Lower risk than most CVEs31th percentile — riskier than 31% of all scored CVEsHighest risk

0.00%0.37%0.74%1.11%0.1%0.4%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from [FIRST.org EPSS](https://www.first.org/epss/).

## Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

216other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

`@sveltejs/kit`npm

5.0Mdownloads / week

## 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.

## Affected Packages

1 total 1 fixed

Ecosystem

Package

Vulnerable range

Fix

📦npm

`@sveltejs/kit` 

all versions

2.57.1`npm install @sveltejs/kit@2.57.1`

## Affected Products

1 product · 1 configurations

Application

`kit`svelte

< 2.57.1

range

## Detection & mitigation playbook

Open-source dependency

1.  ### Detect
    
    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @sveltejs/kit, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
    
2.  ### Fix
    
    Update @sveltejs/kit to 2.57.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-40074 is resolved across your whole dependency graph.
    
3.  ### Workarounds
    
    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
    

## Frequently Asked Questions

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.

O3 Security · Impact-Aware SCA

### Is CVE-2026-40074 in your dependencies?

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