CVE-2026-86205

Summary

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 Software

VendorProductVersion RangeStatus
h3jsh32.0.1-rc.17 < 2.0.1-rc.18affected
h3jsh32.0.1-rc.18unaffected

Weaknesses

  • CWE-601: URL Redirection to Untrusted Site ('Open Redirect')

References