CVE-2026-86205
MEDIUM
NVD
CVSS Score
5.4
Severity
MEDIUM
Published
Sep 06, 2026
Vendor
unknown
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.