CVE-2026-66062: SvelteKit is a framework for rapidly developing robust, performant web applications using Svelte

Routine

MEDIUM 5.3REMOTE

CVE-2026-66062 is a medium-severity flaw (CVSS 5.3) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-1333
Published	2026-08-07
Last modified	2026-10-24

Publisher (CNA): GitHub, Inc.

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-08-07 17:17 UTCPublished CVE record published
2026-10-24 16:10 UTCUpdated Record last modified

Exact fixes by distribution

npm · @sveltejs/kit · FIXED · 2.70.2 · vulnerable: <= 2.70.1 · source

npm install @sveltejs/kit@">=2.70.2" npm ls @sveltejs/kit

Fedora 46 · clementine · FIXED · 1.4.2-1.fc46 · FEDORA-2026-3e748ef4d3 · source

sudo dnf upgrade --advisory=FEDORA-2026-3e748ef4d3

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-66062?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-66062 being exploited?

CVE-2026-66062 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-66062 affect?

CVE-2026-66062 affects affected software. Severity is medium (CVSS 5.3). 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 expres

How urgent is CVE-2026-66062?

Priority 34/100. Remotely exploitable, no login, no user action

References

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