---
id: CVE-2026-66062
title: >-
  SvelteKit is a framework for rapidly developing robust, performant web
  applications using Svelte
summary: >-
  SvelteKit is a framework for rapidly developing robust, performant web
  applications using Svelte. Prior to 2.70.2, the content negotiation header
  parser used by SvelteKit's request handling (for headers such as Accept) uses
  a regular exp…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-1333
vendor: sveltejs
product: '@sveltejs/kit'
affected:
  - '@sveltejs/kit <= 2.70.1'
patched:
  - '@sveltejs/kit 2.70.2'
published: '2026-08-07'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T21:02:22.660'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-66062'
references:
  - url: >-
      https://github.com/sveltejs/kit/commit/82712fc02c24b1dcf5b25d7a52129cd8455f04f5
    label: security-advisories@github.com
  - url: 'https://github.com/sveltejs/kit/releases/tag/@sveltejs/kit@2.70.2'
    label: security-advisories@github.com
  - url: 'https://github.com/sveltejs/kit/security/advisories/GHSA-29g2-3rmr-qm68'
    label: security-advisories@github.com
  - url: 'https://github.com/advisories/GHSA-29g2-3rmr-qm68'
tags:
  - nvd
  - ghsa
  - npm
epss: 0.00291
epssPercentile: 0.21976
aliases:
  - GHSA-29g2-3rmr-qm68
ecosystem: npm
ingestedAt: '2026-08-07T17:15:34.094Z'
---

## Overview

SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte. Prior to 2.70.2, the content negotiation header parser used by SvelteKit's request handling (for headers such as Accept) uses a regular expression vulnerable to quadratic backtracking, so a maliciously crafted header value can cause excessive CPU consumption and degrade or deny service. Version 2.70.2 fixes the issue.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-66062)

Affected packages:

- `@sveltejs/kit <= 2.70.1`

Patched in:

- `@sveltejs/kit 2.70.2`

Source: https://github.com/advisories/GHSA-29g2-3rmr-qm68