Possible Open Redirect Vulnerability in ActionPack Ruby Gem

CVE-2021-22903 · MEDIUM Severity

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

The actionpack ruby gem before 6.1.3.2 suffers from a possible open redirect vulnerability. Specially crafted Host headers in combination with certain "allowed host" formats can cause the Host Authorization middleware in Action Pack to redirect users to a malicious website. This is similar to CVE-2021-22881. Strings in config.hosts that do not have a leading dot are converted to regular expressions without proper escaping. This causes, for example, `config.hosts << "sub.example.com"` to permit a request with a Host header value of `sub-example.com`.

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