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: 0.5% (41st percentile of EPSS-scored CVEs). 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: 0.5%CVSS: 5.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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
5.3MEDIUMmedium confidence
EG Risk
39
EG Risk 39/100CISA SSVC

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%
Exploitation1% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
41st
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 7, 2026

Last Modified

September 9, 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 rangeFix by version rangeDependents
@sveltejs/kit—
  • every version up to 2.70.2: fixed in 2.70.2
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 37× 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. 2026-10-04 05:43 UTCEG score recompute
  2. 2026-10-03 14:26 UTCEPSS rescore
  3. 2026-10-02 17:56 UTCEPSS rescore
  4. 2026-10-02 09:33 UTCEG score recompute
  5. 2026-10-01 19:50 UTCEPSS rescore
  6. 2026-09-30 22:55 UTCEG score recompute
  7. 2026-09-30 15:03 UTCEPSS rescore
  8. 2026-09-29 05:45 UTCEG score recompute
  9. 2026-09-28 13:51 UTCEPSS rescore
  10. 2026-09-27 17:10 UTCEG score recompute
  11. 2026-09-26 15:59 UTCEPSS rescore
  12. 2026-09-25 04:15 UTCEG score recompute
  13. 2026-09-23 17:54 UTCEPSS rescore
  14. 2026-09-23 13:46 UTCEG score recompute
  15. 2026-09-22 12:48 UTCEG score recompute
  16. 2026-09-21 12:03 UTCEG score recompute
  17. 2026-09-20 20:16 UTCEPSS rescore
  18. 2026-09-20 05:20 UTCEG score recompute
  19. 2026-09-19 04:53 UTCEG score recompute
  20. 2026-09-18 19:28 UTCEPSS rescore
  21. 2026-09-18 04:25 UTCEG score recompute
  22. 2026-09-17 03:58 UTCEG score recompute
  23. 2026-09-16 14:08 UTCEPSS rescore
  24. 2026-09-16 05:15 UTCEPSS rescore
  25. 2026-09-16 03:30 UTCEG score recompute
Show 63 more
  1. 2026-09-14 02:26 UTCEG score recompute
  2. 2026-09-13 01:59 UTCEG score recompute
  3. 2026-09-12 01:31 UTCEG score recompute
  4. 2026-09-11 09:37 UTCEPSS rescore
  5. 2026-09-11 01:03 UTCEG score recompute
  6. 2026-09-09 06:00 UTCEG score recompute
  7. 2026-09-08 22:01 UTCEPSS rescore
  8. 2026-09-07 17:44 UTCEG score recompute
  9. 2026-09-07 16:01 UTCEPSS rescore
  10. 2026-09-06 13:47 UTCEPSS rescore
  11. 2026-09-06 09:59 UTCEG score recompute
  12. 2026-09-05 15:31 UTCEPSS rescore
  13. 2026-09-05 09:32 UTCEG score recompute
  14. 2026-09-04 09:04 UTCEG score recompute
  15. 2026-09-04 05:07 UTCEPSS rescore
  16. 2026-09-03 06:00 UTCEG score recompute
  17. 2026-09-02 14:12 UTCEPSS rescore
  18. 2026-09-01 22:55 UTCEG score recompute
  19. 2026-09-01 13:54 UTCEPSS rescore
  20. 2026-09-01 04:40 UTCEPSS rescore
  21. 2026-08-31 22:27 UTCEG score recompute
  22. 2026-08-30 19:17 UTCEPSS rescore
  23. 2026-08-30 16:26 UTCEG score recompute
  24. 2026-08-30 01:22 UTCEPSS rescore
  25. 2026-08-29 15:58 UTCEG score recompute
  26. 2026-08-28 21:42 UTCEPSS rescore
  27. 2026-08-28 11:53 UTCEG score recompute
  28. 2026-08-27 07:50 UTCEG score recompute
  29. 2026-08-26 14:47 UTCEPSS rescore
  30. 2026-08-26 07:09 UTCEG score recompute
  31. 2026-08-25 13:49 UTCEPSS rescore
  32. 2026-08-25 06:39 UTCEG score recompute
  33. 2026-08-23 05:34 UTCEG score recompute
  34. 2026-08-23 00:19 UTCEPSS rescore
  35. 2026-08-22 05:07 UTCEG score recompute
  36. 2026-08-21 23:49 UTCEPSS rescore
  37. 2026-08-21 04:39 UTCEG score recompute
  38. 2026-08-20 22:56 UTCEPSS rescore
  39. 2026-08-20 04:11 UTCEG score recompute
  40. 2026-08-19 17:04 UTCEPSS rescore
  41. 2026-08-19 03:41 UTCEG score recompute
  42. 2026-08-18 13:48 UTCEPSS rescore
  43. 2026-08-18 03:11 UTCEG score recompute
  44. 2026-08-17 13:47 UTCEPSS rescore
  45. 2026-08-17 02:40 UTCEG score recompute
  46. 2026-08-16 14:56 UTCEPSS rescore
  47. 2026-08-15 01:45 UTCEG score recompute
  48. 2026-08-15 01:30 UTCEPSS rescore
  49. 2026-08-14 01:18 UTCEG score recompute
  50. 2026-08-13 22:00 UTCEPSS rescore
  51. 2026-08-13 00:50 UTCEG score recompute
  52. 2026-08-12 13:51 UTCEPSS rescore
  53. 2026-08-12 00:23 UTCEG score recompute
  54. 2026-08-11 00:00 UTCEPSS rescore
  55. 2026-08-09 23:28 UTCEG score recompute
  56. 2026-08-09 13:47 UTCEPSS rescore
  57. 2026-08-08 23:01 UTCEG score recompute
  58. 2026-08-08 16:37 UTCEPSS rescore
  59. 2026-08-07 22:33 UTCEG score recompute
  60. 2026-08-07 21:22 UTCEG score recompute
  61. 2026-08-07 17:25 UTCEG score recompute
  62. 2026-08-07 17:07 UTCEG score recompute
  63. 2026-08-07 17:07 UTCMITRE cvelistV5first tracked

Related CVEs(same product + same CWE)

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 on August 7, 2026, with the most recent update on September 9, 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 0.5% probability of exploitation in the next 30 days (41st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-66062?
CVE-2026-66062 has a CVSS base score of 5.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-66062?
A fix for CVE-2026-66062 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-66062 are linked in the Vendor Advisories panel on this page.

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