OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. Prior to 4.0.0, the client_credentials and Resource Owner Password Credentials token grant handlers can authenticate request.client as one confidential client while retaining an attacker-supplied request.client_id for validate_grant_type and validate_scopes. A lower-privilege authenticated client can therefore cause grant and scope authorization to use another client's identity when an application validator relies on the documented client_id argument, potentially issuing tokens with unauthorized grants or scopes. Validators that authorize exclusively from request.client may not be affected. This issue is fixed in version 4.0.0.
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Affected Vendors & Products
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History
Tue, 03 Nov 2026 14:30:00 +0000
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ssvc
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Fri, 30 Oct 2026 23:45:00 +0000
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Oauthlib
Oauthlib oauthlib |
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Oauthlib
Oauthlib oauthlib |
Fri, 30 Oct 2026 12:30:00 +0000
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| Weaknesses | CWE-807 | |
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threat_severity
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cvssV3_1
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Wed, 28 Oct 2026 21:30:00 +0000
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| Description | OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. Prior to 4.0.0, the client_credentials and Resource Owner Password Credentials token grant handlers can authenticate request.client as one confidential client while retaining an attacker-supplied request.client_id for validate_grant_type and validate_scopes. A lower-privilege authenticated client can therefore cause grant and scope authorization to use another client's identity when an application validator relies on the documented client_id argument, potentially issuing tokens with unauthorized grants or scopes. Validators that authorize exclusively from request.client may not be affected. This issue is fixed in version 4.0.0. | |
| Title | OAuthLib: Token grants can use attacker-supplied client_id for authorization after authenticating a different client | |
| Weaknesses | CWE-863 | |
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| Metrics |
cvssV4_0
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Status: PUBLISHED
Assigner: GitHub_M
Published: 2026-10-28T21:09:58.893Z
Updated: 2026-11-03T13:38:35.048Z
Reserved: 2026-10-28T17:25:37.562Z
Link: CVE-2026-118669
Updated: 2026-11-03T13:38:28.111Z
Status : Awaiting Analysis
Published: 2026-10-28T22:17:12.610
Modified: 2026-11-03T14:17:32.237
Link: CVE-2026-118669