CVE-2026-66062 | BDVDB-2026-356365 Detail

sveltejskit

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.

Impact#

Per CVSS v3.1: confidentiality impact none, integrity impact none, availability impact low. Attack vector: network.

Weaknesses#

CWE-1333 Inefficient Regular Expression Complexity

References#

Exploit#

No public exploit known

History#

Version 12026-08-07Record published in the CVE List.

Published

Published: 2026-08-07
Last modified: 2026-08-07

Vendor information

Vendor: sveltejs
Product: kit

All sveltejs vulnerabilities

Score

5.3 Medium

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 43.6.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Not classified

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
< 2.70.2
Fixed
Not stated

Scoring System

CVSS v4.0

Not available

CVSS v3.1

5.3 Medium

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Metric breakdown
Attack Vector	Network
Attack Complexity	Low
Privileges Required	None
User Interaction	None
Scope	Unchanged
Confidentiality	None
Integrity	None
Availability	Low

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).