CVE-2026-66062

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 78% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.3Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
5.3
EG Score
5.3(medium)
EG Risk
39(Track)
EG Risk 39/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity53% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
22%
KEV
Not listed

Published

August 7, 2026

Last Modified

August 7, 2026

Advisory Details (2)

Auto-updated Aug 7, 2026
Patch available. Sources: github, github_commit.
github_commit Patch Available

commit 82712fc02c24 (sveltejs/kit)

Patch available: sveltejs/kit @sveltejs/[email protected] (contains commit 82712fc02c24)

https://github.com/sveltejs/kit/commit/82712fc02c24b1dcf5b25d7a52129cd8455f04f5
github Patch Available

ReDoS in SvelteKit content negotiation header parsing · Advisory · sveltejs/kit · GitHub

https://github.com/sveltejs/kit/security/advisories/GHSA-29g2-3rmr-qm68

Vendor Advisories for CVE-2026-66062(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
@sveltejs/kit—2.70.2—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 27× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-21 04:39 UTCEG score recompute
  2. 2026-08-20 22:56 UTCEPSS rescore
  3. 2026-08-20 04:11 UTCEG score recompute
  4. 2026-08-19 17:04 UTCEPSS rescore
  5. 2026-08-19 03:41 UTCEG score recompute
  6. 2026-08-18 13:48 UTCEPSS rescore
  7. 2026-08-18 03:11 UTCEG score recompute
  8. 2026-08-17 13:47 UTCEPSS rescore
  9. 2026-08-17 02:40 UTCEG score recompute
  10. 2026-08-16 14:56 UTCEPSS rescore
  11. 2026-08-15 01:45 UTCEG score recompute
  12. 2026-08-15 01:30 UTCEPSS rescore
  13. 2026-08-14 01:18 UTCEG score recompute
  14. 2026-08-13 22:00 UTCEPSS rescore
  15. 2026-08-13 00:50 UTCEG score recompute
  16. 2026-08-12 13:51 UTCEPSS rescore
  17. 2026-08-12 00:23 UTCEG score recompute
  18. 2026-08-11 00:00 UTCEPSS rescore
  19. 2026-08-09 23:28 UTCEG score recompute
  20. 2026-08-09 13:47 UTCEPSS rescore
  21. 2026-08-08 23:01 UTCEG score recompute
  22. 2026-08-08 16:37 UTCEPSS rescore
  23. 2026-08-07 22:33 UTCEG score recompute
  24. 2026-08-07 21:22 UTCEG score recompute
  25. 2026-08-07 17:25 UTCEG score recompute
Show 2 more
  1. 2026-08-07 17:07 UTCEG score recompute
  2. 2026-08-07 17:07 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-66062?
CVE-2026-66062 is a medium vulnerability published on August 7, 2026. 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…
When was CVE-2026-66062 disclosed?
CVE-2026-66062 was first published in the National Vulnerability Database on August 7, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-66062 actively exploited?
CVE-2026-66062 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 78.2% of all scored CVEs.
What is the CVSS score of CVE-2026-66062?
CVE-2026-66062 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-66062?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-66062, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-66062

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