CVE-2026-86253

Medium

Description

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.

SeverityMedium

CVSS5.9

Exploit probability—

ProductH3

PublishedSep 6, 2026

First seenSep 6, 2026

Weakness typeCWE-22Path traversal

How to fix

Update

h32.0.1-rc.15, 1.15.6 or later

Vendor advisories

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

Affected products

Product	Affected versions	Fixed in
h3npm	2.0.0 ≤ v < 2.0.1-rc.15, v < 1.15.6	2.0.1-rc.15, 1.15.6

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