CVE-2026-86205
Published:September 06, 2026
Updated:September 22, 2026
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.
Affected Packages
https://github.com/h3js/h3.git (GITHUB):
Affected version(s) =v2.0.1-rc.17 <v2.0.1-rc.18Fix Suggestion:
Update to version v2.0.1-rc.18h3 (NPM):
Affected version(s) =2.0.1-rc.17 <2.0.1-rc.18Fix Suggestion:
Update to version 2.0.1-rc.18Related Resources (7)
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Contact UsCVSS v4
Base Score:
5.3
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
PASSIVE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
LOW
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
5.4
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Weakness Type (CWE)
URL Redirection to Untrusted Site ('Open Redirect')
EPSS
Base Score:
0.20