CVE-2026-54603

OAuth2::Client#request: Protocol-relative redirect Location overrides authority, leaking bearer Authorization to attacker host

HIGH
8.6
CVSS Score
Published: July 28, 2026 at 04:29 PM UTC
Updated: October 23, 2026 at 11:10 PM UTC
1 product affected across 1 vendorOAUTH2

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Severity
HIGH8.6
Exploit prediction
EPSS 0.4%
SSVC
PoC

Description

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

>= 0.4.0, < 2.0.22
Affected range stops below 2.0.22, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.6HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-200CWE-601

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