h3 versions before 2.0.1-rc.18 contain an open redirect vulnerability in the redirectBack() utility that fails to sanitize protocol-relative paths in the Referer header pathname. Attackers can craft a same-origin URL with a double-slash path segment that passes origin validation but produces a Location header interpreted by browsers as a protocol-relative redirect to an external domain.
History

Tue, 08 Sep 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Sun, 06 Sep 2026 13:45:00 +0000

Type Values Removed Values Added
First Time appeared H3js
H3js h3
Vendors & Products H3js
H3js h3

Sun, 06 Sep 2026 12:15:00 +0000

Type Values Removed Values Added
Description h3 versions before 2.0.1-rc.18 contain an open redirect vulnerability in the redirectBack() utility that fails to sanitize protocol-relative paths in the Referer header pathname. Attackers can craft a same-origin URL with a double-slash path segment that passes origin validation but produces a Location header interpreted by browsers as a protocol-relative redirect to an external domain.
Title h3 before 2.0.1-rc.18 Open Redirect via redirectBack()
Weaknesses CWE-601
References
Metrics cvssV3_1

{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N'}

cvssV4_0

{'score': 5.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published: 2026-09-06T12:00:25.530Z

Updated: 2026-09-08T13:28:55.791Z

Reserved: 2026-09-05T11:52:36.822Z

Link: CVE-2026-86205

cve-icon Vulnrichment

Updated: 2026-09-08T13:28:23.543Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-09-06T12:17:15.277

Modified: 2026-09-08T20:00:18.870

Link: CVE-2026-86205

cve-icon Redhat

No data.