Not a U.S. government website. NDD is an independent vulnerability database by Volerion and is not affiliated with or endorsed by NIST or NVD.

CVE-2026-86251 Details

Description

h3 versions before 1.15.9 contain a path traversal vulnerability in the serveStatic utility. A double-decoding flaw allows a request path containing double-encoded dot sequences (e.g. %252e%252e) to be decoded to %2e%2e, which survives resolveDotSegments() because that function only checks for literal '.' characters. When the resulting asset ID is resolved by URL-based backends (CDN, S3, object storage), %2e%2e is interpreted as '..' per RFC 3986, enabling path traversal to read arbitrary files from the backend.

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: [email protected]CVSS-B:5.9 MEDIUMVector:CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

References to Advisories, Solutions, and Tools

By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.

URL	Source(s)	Tag(s)
https://github.com/h3js/h3/security/advisories/GHSA-72gr-qfp7-vwhw	CISA-ADP
https://github.com/h3js/h3/security/advisories/GHSA-72gr-qfp7-vwhw	[email protected]
https://www.vulncheck.com/advisories/h3-before-1.15.9-path-traversal-via-double-decoding	[email protected]

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-22	Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')	[email protected]

Affected Products

No affected product data is available for this CVE.

Change History

2 change records found show changes

Date	Action	Recorded By
Sep 9, 2026	CVE Modified	CISA-ADP
Sep 6, 2026	New CVE Received	[email protected]