CVE-2026-66062: medium-severity vulnerability in sveltejs kit
SvelteKit: ReDoS (O(n^2)) in content negotiation — unauthenticated DoS via the Accept header
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.3epss 0.5%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Affected products
sveltejs · kitRelated CVEs — sveltejs kit
In the same product, most dangerous first.
CVE-2024-23641HIGHSending a GET or HEAD request with a body crashes SvelteKitEPSS 0.8%CVE-2025-67647HIGHSvelteKit Denial of service and possible SSRF when using prerenderingEPSS 0.6%CVE-2026-22803HIGHSvelteKit has a memory amplification DoS in Remote Functions binary form deserializerEPSS 0.6%CVE-2023-29003HIGHSvelteKit has Insufficient Cross-Site Request Forgery ProtectionEPSS 0.6%CVE-2026-40073HIGHSvelteKit has a BODY_SIZE_LIMIT bypass in @sveltejs/adapter-nodeEPSS 0.5%CVE-2026-82259HIGHSvelteKit 2.49.0 before 2.53.3 Denial of Service via formEPSS 0.5%