SvelteJS Kit up to 2.70.1 Content Negotiation Header Parser resource consumption

Summaryinfo

A vulnerability was found in SvelteJS Kit up to 2.70.1. It has been rated as problematic. Impacted is an unknown function of the component Content Negotiation Header Parser. Performing a manipulation results in resource consumption. This vulnerability is identified as CVE-2026-66062. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in SvelteJS Kit up to 2.70.1. It has been classified as problematic. This affects an unknown function of the component Content Negotiation Header Parser. The manipulation with an unknown input leads to a resource consumption vulnerability. CWE is classifying the issue as CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. This is going to have an impact on availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-66062 since 07/24/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 2.70.2 eliminates this vulnerability.

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Productinfo

Vendor

• SvelteJS

Name

• Kit

Version

• 2.70.0
• 2.70.1

Website

• Product: https://github.com/sveltejs/kit/

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CPE 2.2info

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