CVE-2026-86253

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure.

Exploit odds

0.6% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-06 12:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-09-10 16:18 UTC Last updatedMost recent change to the record

Details

Published

2026-09-06 12:17 UTC

Last modified

2026-09-10 16:18 UTC

Exploit probability

0.6% · EPSS, next 30 days

Weakness

CWE-22 · Path traversal

Record status

Awaiting Analysis

Attack profile CVSS 4.0 · 8.2

Attack vector

Network

Complexity

High

Attack requirements

Present

Privileges needed

None

User interaction

None

Confidentiality

High

Integrity

None

Availability

None