CVE-2026-86253

MEDIUMPre-NVD 5.95.9
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 5.9 from GitHub Security Advisory (severity: HIGH) published 2026-09-06. A secondary CVSS source baseline 5.9; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source

Also known asEUVD-2026-72109 (ENISA EUVD) · GHSA-jh84-7pcc-38gf (GitHub Security Advisories)Source: ENISA EUVD

5.9EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 5.9Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

h3 (npm package) versions <= 2.0.1-rc.14 contain a path traversal vulnerability in serveStatic(). On Node.js deployments, event.url.pathname is not normalized, so percent-encoded dot segments (%2e%2e) are passed to decodeURI() and decoded to ../ sequences without sanitization. An unauthenticated remote attacker can send crafted requests to endpoints served by serveStatic() to read arbitrary files outside the intended static directory. Fixed in 1.15.6 and 2.0.1-rc.15.

CVSS v3
5.9
EG Score
5.9MEDIUMmedium confidence
EG Risk
27
EG Risk 27/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity59% × 45%
Impact severity (EG Severity): CVSS 5.9 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.6% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.6%
EPSS %ILE
50th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (5.9): severity, escalated by confirmed exploitation. This CVE's 5.9 is its impact severity (EG Severity), not escalated.

EG Severity
5.9 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

September 6, 2026

Last Modified

September 10, 2026

Advisory Details (2)

Auto-updated Sep 6, 2026
Patch available. Sources: github.
Web page

h3 before 1.15.6 Path Traversal via Percent-Encoded Dot Segments | Advisories | VulnCheck

https://www.vulncheck.com/advisories/h3-before-1.15.6-path-traversal-via-percent-encoded-dot-segments
GitHub advisoryMentions a patch (unverified)

Path Traversal via Percent-Encoded Dot Segments in serveStatic Allows Arbitrary File Read · Advisory · h3js/h3 · GitHub

https://github.com/h3js/h3/security/advisories/GHSA-wr4h-v87w-p3r7

Vendor Advisories for CVE-2026-86253(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
h3—
  • 2.0.0 up to 2.0.1-rc.15: fixed in 2.0.1-rc.15
  • every version up to 1.15.6: fixed in 1.15.6
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 32× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 142 rows on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 42 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-12 16:34 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  2. 2026-11-11 16:41 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  3. 2026-11-10 16:45 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  4. 2026-11-09 16:36 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  5. 2026-11-08 16:41 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  6. 2026-11-07 16:40 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  7. 2026-11-06 16:39 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  8. 2026-11-05 16:38 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  9. 2026-11-04 16:37 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  10. 2026-11-03 16:49 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  11. 2026-11-02 16:46 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  12. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  13. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  14. 2026-10-30 16:35 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  15. 2026-10-29 23:55 UTCOSV refresh
  16. 2026-10-29 16:34 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  17. 2026-10-28 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  18. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  19. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  20. 2026-10-25 16:34 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  21. 2026-10-25 13:55 UTCEchelonGraph re-scored
  22. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  23. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  24. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  25. 2026-10-22 12:46 UTCEchelonGraph re-scored
Show 75 more
  1. 2026-10-22 12:46 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  2. 2026-10-21 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  3. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  4. 2026-10-19 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  5. 2026-10-18 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  6. 2026-10-18 03:05 UTCEchelonGraph re-scored
  7. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  8. 2026-10-16 16:44 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  9. 2026-10-15 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  10. 2026-10-14 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  11. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  12. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  13. 2026-10-12 14:51 UTCEchelonGraph re-scored
  14. 2026-10-11 19:17 UTCEchelonGraph re-scored
  15. 2026-10-11 16:33 UTCEchelonGraph re-scored
  16. 2026-10-11 13:51 UTCEchelonGraph re-scored
  17. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  18. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  19. 2026-10-09 22:53 UTCEchelonGraph re-scored
  20. 2026-10-09 22:53 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  21. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  22. 2026-10-09 00:59 UTCEchelonGraph re-scored
  23. 2026-10-09 00:58 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  24. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  25. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  26. 2026-10-07 22:48 UTCEchelonGraph re-scored
  27. 2026-10-07 22:48 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  28. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  29. 2026-10-06 14:41 UTCEchelonGraph re-scored
  30. 2026-10-06 14:41 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  31. 2026-10-05 17:44 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  32. 2026-10-05 16:38 UTCEchelonGraph re-scored
  33. 2026-10-05 16:38 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  34. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  35. 2026-10-04 17:36 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  36. 2026-10-03 19:13 UTCEchelonGraph re-scored
  37. 2026-10-03 19:13 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  38. 2026-10-02 20:53 UTCEchelonGraph re-scored
  39. 2026-10-02 20:53 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  40. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  41. 2026-10-01 22:43 UTCEchelonGraph re-scored
  42. 2026-10-01 22:43 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  43. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  44. 2026-10-01 00:53 UTCEchelonGraph re-scored
  45. 2026-10-01 00:53 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  46. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  47. 2026-09-30 02:35 UTCEchelonGraph re-scored
  48. 2026-09-30 02:35 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  49. 2026-09-28 22:19 UTCEchelonGraph re-scored
  50. 2026-09-28 22:19 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  51. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  52. 2026-09-28 00:29 UTCEchelonGraph re-scored
  53. 2026-09-28 00:29 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  54. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  55. 2026-09-27 02:38 UTCEchelonGraph re-scored
  56. 2026-09-27 02:38 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  57. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  58. 2026-09-26 04:46 UTCEchelonGraph re-scored
  59. 2026-09-26 04:46 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  60. 2026-09-25 06:53 UTCEchelonGraph re-scored
  61. 2026-09-25 06:53 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  62. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  63. 2026-09-24 09:02 UTCEchelonGraph re-scored
  64. 2026-09-24 09:02 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  65. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  66. 2026-09-23 11:12 UTCEchelonGraph re-scored
  67. 2026-09-23 11:12 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  68. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  69. 2026-09-22 13:21 UTCEchelonGraph re-scored
  70. 2026-09-22 13:20 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  71. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  72. 2026-09-21 15:29 UTCEchelonGraph re-scored
  73. 2026-09-21 15:29 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9
  74. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  75. 2026-09-20 17:38 UTCGHSA enrichmentGHSA-jh84-7pcc-38gf · GitHub severity HIGH · GitHub CVSS 5.9

Frequently asked(5)

What is CVE-2026-86253?
CVE-2026-86253 is a medium-severity vulnerability; its CVE record was published on September 6, 2026. h3 (npm package) versions <= 2.0.1-rc.14 contain a path traversal vulnerability in serveStatic(). On Node.js deployments, event.url.pathname is not normalized, so percent-encoded dot segments (%2e%2e) are passed to decodeURI() and decoded to ../ sequences without sanitization. An unauthenticated…
When was CVE-2026-86253 made public?
CVE-2026-86253 was made public on March 17, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on September 6, 2026. EchelonGraph's copy of the record carries a last-modified date of September 10, 2026; the record at its source may have been updated since.
Is CVE-2026-86253 actively exploited?
CVE-2026-86253 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (50th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-86253?
CVE-2026-86253 has a CVSS base score of 5.9 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-86253?
A fix for CVE-2026-86253 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-86253 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-86253

Explore →

Is Your Infrastructure Affected by CVE-2026-86253?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.