{"id":"CVE-2026-118669","state":"PUBLISHED","title":"OAuthLib: Token grants can use attacker-supplied client_id for authorization after authenticating a different client","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.","publishedAt":"2026-10-28T21:09:58.893Z","updatedAt":"2026-10-28T21:09:58.893Z","severity":{"score":8.4,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["oauthlib oauthlib"],"affected":[{"vendor":"oauthlib","product":"oauthlib","versions":[{"version":"< 4.0.0","status":"affected"}]}],"references":["https://github.com/oauthlib/oauthlib/security/advisories/GHSA-7984-qgvg-3j9c","https://github.com/oauthlib/oauthlib/pull/920","https://github.com/oauthlib/oauthlib/commit/c951a1d09f99f14e3240973fa83c4f4287d4753d","https://github.com/oauthlib/oauthlib/releases/tag/v4.0.0"],"weaknesses":["CWE-863"],"ingestedAt":"2026-10-29T20:10:52.580Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/118xxx/CVE-2026-118669.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-118669","state":"PUBLISHED","datePublished":"2026-10-28T21:09:58.893Z","dateUpdated":"2026-10-28T21:09:58.893Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-10-28T17:25:37.562Z"},"containers":{"cna":{"title":"OAuthLib: Token grants can use attacker-supplied client_id for authorization after authenticating a different client","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"oauthlib","product":"oauthlib","versions":[{"version":"< 4.0.0","status":"affected"}]}],"references":[{"url":"https://github.com/oauthlib/oauthlib/security/advisories/GHSA-7984-qgvg-3j9c","name":"https://github.com/oauthlib/oauthlib/security/advisories/GHSA-7984-qgvg-3j9c","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/oauthlib/oauthlib/pull/920","name":"https://github.com/oauthlib/oauthlib/pull/920","tags":["x_refsource_MISC"]},{"url":"https://github.com/oauthlib/oauthlib/commit/c951a1d09f99f14e3240973fa83c4f4287d4753d","name":"https://github.com/oauthlib/oauthlib/commit/c951a1d09f99f14e3240973fa83c4f4287d4753d","tags":["x_refsource_MISC"]},{"url":"https://github.com/oauthlib/oauthlib/releases/tag/v4.0.0","name":"https://github.com/oauthlib/oauthlib/releases/tag/v4.0.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"LOW","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"HIGH","subIntegrityImpact":"HIGH","subAvailabilityImpact":"NONE","baseScore":8.4,"baseSeverity":"HIGH","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-863","lang":"en","description":"CWE-863: Incorrect Authorization","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-28T21:09:58.893Z"},"source":{"advisory":"GHSA-7984-qgvg-3j9c","discovery":"UNKNOWN"}}}}}