CVE-2026-86253CWE-22

h3 before 1.15.6 Path Traversal via Percent-Encoded Dot Segments

Medium · published September 6, 2026

CVSS v3.1
5.9
EPSS
—
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.9 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS v4.0
8.2 · CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
EPSS
Not scored
Weakness
CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Published
2026-09-06T12:00Z
Timeline
  • 06 SEP 12:00Z
    h3 before 1.15.6 Path Traversal via Percent-Encoded Dot Segments
    cvelistv5