Bug 2567703 (CVE-2026-49272)

Summary: CVE-2026-49272 oauthlib: oauthlib: Authentication bypass via missing device code validation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in OAuthLib. This vulnerability allows a remote attacker to bypass authentication and obtain unauthorized access tokens during the device authorization workflow. By submitting a token request with a valid client identifier alongside an invalid or missing device authorization code, the attacker can receive a valid bearer token without completing user approval, leading to unauthorized access to protected resources.
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Description OSIDB Bzimport 2026-11-05 22:19:23 UTC 
OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. From 3.3.0 until 4.0.1, OAuthLib's RFC 8628 device workflow does not require DeviceCodeGrant.validate_token_request to check that the device_code parameter is present and valid. A caller whose client request is accepted by the configured validator and who knows a valid client ID enabled for the device workflow can submit a missing or bogus device code to the token endpoint and obtain a bearer token without completing device authorization. This issue is fixed in version 4.0.1.