CVE-2026-66062: SvelteKit: ReDoS (O(n^2)) in content negotiation — unauthenticated DoS via the Accept header

August 7, 2026

SvelteKit is vulnerable to remote CPU-exhaustion DoS attacks via specifically-crafted Accept headers. The impact is mitigated by default header length limits on most platforms, but in the case of raised or absent limits a denial of service is possible.

References

github.com/advisories/GHSA-29g2-3rmr-qm68
github.com/sveltejs/kit/commit/82712fc02c24b1dcf5b25d7a52129cd8455f04f5
github.com/sveltejs/kit/releases/tag/@sveltejs/kit@2.70.2
github.com/sveltejs/kit/security/advisories/GHSA-29g2-3rmr-qm68
nvd.nist.gov/vuln/detail/CVE-2026-66062

Code Behaviors & Features

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