CVE-2026-54603: Ruby-OAuth OAUTH2

High severity, CVSS 8.6. EPSS: 0.4% chance of exploitation in the next 30 days.

OAuth2 is a Ruby wrapper for the OAuth 2.0 and 2.1 authorization frameworks, including OpenID Connect (OIDC). From 0.4.0 to 2.0.21, a protocol-relative redirect Location returned to OAuth2::Client#request overrides the request authority, so the bearer Authorization header is sent to an attacker-controlled host, leaking the credential. This issue is fixed in version 2.0.22.

Affected products

• Ruby-OAuth OAUTH2: from 0.4.0, before 2.0.22 (fixed in 2.0.22)

Published 2026-07-28. Last modified 2026-10-05.