CVE-2026-66062SvelteKit: ReDoS (O(n^2)) in content negotiation — unauthenticated DoS via the Accept header
- 5.3MediumCVSS base score
- 0.51%Exploitation in 30 daysEPSS · top 56% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By GitHub_M
- 15 days later
· 15 days later
Published
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
| NVDNVD · Deferred | 3.1 | Medium5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
- EPSS (exploitation in 30 days)
- 0.51% · top 56% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- npm@sveltejs/kitGHSA-29g2-3rmr-qm68 (opens in a new tab)
References
References3
- https://github.com/sveltejs/kit/security/advisories/GHSA-29g2-3rmr-qm68 (opens in a new tab)x_refsource_CONFIRM
- https://github.com/sveltejs/kit/commit/82712fc02c24b1dcf5b25d7a52129cd8455f04f5 (opens in a new tab)x_refsource_MISC
- https://github.com/sveltejs/kit/releases/tag/@sveltejs/[email protected] (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-54557 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-29g2-3rmr-qm68 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-66062)Record last updated .