What is CVE-2026-66062?

CVE-2026-66062 is a medium-severity vulnerability in Sveltejs Kit, classified under Inefficient Regular Expression Complexity. CVSS score: 5.3/10. Published 2026-08-07.

How severe is CVE-2026-66062?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Sveltejs Kit

CVE-2026-66062

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 expre…

Vulnerability class: ReDoS (Regular Expression Denial of Service)

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

Affected products

Sveltejs Kit — versions < 2.70.2

Weakness classification (CWE)

CWE-1333 — Inefficient Regular Expression Complexity

References

security-advisories@github.com (x_refsource_MISC)
security-advisories@github.com (x_refsource_MISC)
security-advisories@github.com (x_refsource_CONFIRM)

Frequently asked questions

What is CVE-2026-66062?: CVE-2026-66062 is a medium-severity vulnerability in Sveltejs Kit, classified under Inefficient Regular Expression Complexity. CVSS score: 5.3/10. Published 2026-08-07.
How severe is CVE-2026-66062?: Medium severity. CVSS v3 base score is 5.3 out of 10.