CVE-2026-66062 Details
Description
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.
A denial-of-service vulnerability has been identified in SvelteKit versions prior to 2.70.2. The issue arises in the content negotiation header parser, which processes headers like 'Accept'. The parser's regular expression is susceptible to quadratic backtracking, allowing a maliciously crafted header value to cause excessive CPU usage, thereby degrading or denying service. While most platforms have default header length limits that can mitigate this issue, the vulnerability can be exploited if these limits are raised or absent.
Users can upgrade to SvelteKit version 2.70.2 or later, where this vulnerability has been patched.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Aug 7, 2026CISA-ADP
Assessed Aug 7, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/sveltejs/kit/commit/82712fc02c24b1dcf5b25d7a52129cd8455f04f5 | [email protected] | Source CodeVendor |
| https://github.com/sveltejs/kit/releases/tag/@sveltejs/[email protected] | [email protected] | Release NotesVendor |
| https://github.com/sveltejs/kit/security/advisories/GHSA-29g2-3rmr-qm68 | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-1333 | Inefficient Regular Expression Complexity | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| SvelteKit | < 2.70.2 (semver) |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Aug 7, 2026 | CVE Modified | CISA-ADP |
| Aug 7, 2026 | New CVE Received | [email protected] |