CVE-2026-86205

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.

CVSS v3 5.4 MEDIUM

5.4^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.5

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/h3js/h3/security/advisories/GHSA-fp4x-ggrf-wmc6
https://www.vulncheck.com/advisories/h3-before-2.0.1-rc.18-open-redirect-via-redirectback
https://github.com/h3js/h3/security/advisories/GHSA-fp4x-ggrf-wmc6

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-06 12:17

Updated : 2026-09-08 20:00

NVD link : CVE-2026-86205

Mitre link : CVE-2026-86205

CVE.ORG link : CVE-2026-86205

JSON object : View

Products Affected

No product.

CWE

CWE-601

URL Redirection to Untrusted Site ('Open Redirect')

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