CVE-2026-66062CWE-1333

CVE-2026-66062

Medium · published August 7, 2026

CVSS v3.1
5.3
EPSS
1%
Percentile
42.3
In the wild
Unconfirmed
What it 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.

The record
Technical detail
CVSS v3.1
5.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS v4.0
Not supplied
EPSS
0.00507 · 42.3th percentile
Weakness
CWE-1333 · Inefficient Regular Expression Complexity
Published
2026-08-07T21:17Z
References (3)
https://github.com/sveltejs/kit/commit/82712fc02c24b1dcf5b25d7a52129cd8455f04f5 · [email protected]https://github.com/sveltejs/kit/releases/tag/@sveltejs/[email protected] · [email protected]https://github.com/sveltejs/kit/security/advisories/GHSA-29g2-3rmr-qm68 · [email protected]
EPSS history
Timeline
  • 07 AUG 16:49Z
    SvelteKit: ReDoS (O(n^2)) in content negotiation — unauthenticated DoS via the Accept header
    cvelistv5