VULNERABILITY INTELLIGENCE

CVE-2021-22903

CVSS score6.1 MEDIUM

EPSS probability1.23%

CISA KEVNot currently listed

Published2021-06-11

Last modified2026-06-17

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

Description

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`.

Weakness classification

support@hackerone.com: CWE-601
nvd@nist.gov: CWE-601

Primary references

support@hackerone.com — Mitigation, Patch, Vendor Advisory
support@hackerone.com — Permissions Required, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108 — Mitigation, Patch, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108 — Permissions Required, Third Party Advisory