Bug 2508093 (CVE-2026-54603)

Summary: CVE-2026-54603 oauth2: OAuth2: Credential leakage via protocol-relative redirect
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: akostadi, amasferr, dmayorov, jlledo, pantinor, tsedmik
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in OAuth2, a Ruby wrapper for the OAuth 2.0 and 2.1 authorization frameworks. When an application uses `OAuth2::Client#request` and receives a protocol-relative redirect (e.g., `//attacker.example/leak`), the request authority can be overridden. This allows a remote attacker to redirect the bearer Authorization header, which contains sensitive credentials, to a malicious host. Consequently, this leads to the unauthorized disclosure of user credentials.
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Description OSIDB Bzimport 2026-07-28 17:45:08 UTC 
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.