{"id":"CVE-2026-53512","state":"PUBLISHED","title":"Better Auth: OAuth refresh-token replay via missing client authentication on oidc-provider and mcp plugins","description":"Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, the legacy oidcProvider and mcp plugins expose OAuth token endpoints whose refresh_token grant authenticates only possession of the bound refreshToken row and matching client_id, without verifying the confidential client's client_secret, allowing an attacker with a valid refresh_token to mint access tokens and rotated refresh tokens through /api/auth/oauth2/token or /api/auth/mcp/token. The @better-auth/oauth-provider package is not affected. This issue is fixed in version 1.6.11.","publishedAt":"2026-07-15T17:18:09.512Z","updatedAt":"2026-07-18T01:08:08.419Z","severity":{"score":9.1,"label":"Critical","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["better-auth better-auth"],"affected":[{"vendor":"better-auth","product":"better-auth","versions":[{"version":"< 1.6.11","status":"affected"}]}],"references":["https://github.com/better-auth/better-auth/security/advisories/GHSA-pw9m-5jxm-xr6h","https://github.com/better-auth/better-auth/pull/9576","https://github.com/better-auth/better-auth/commit/1f2ff4215c4affff0b140b0c0a712c0dde35659c","https://github.com/better-auth/better-auth/releases/tag/v1.6.11"],"weaknesses":["CWE-287","CWE-306","CWE-345","CWE-863"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/53xxx/CVE-2026-53512.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53512","state":"PUBLISHED","datePublished":"2026-07-15T17:18:09.512Z","dateUpdated":"2026-07-18T01:08:08.419Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-09T17:30:33.455Z"},"containers":{"cna":{"title":"Better Auth: OAuth refresh-token replay via missing client authentication on oidc-provider and mcp plugins","descriptions":[{"lang":"en","value":"Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, the legacy oidcProvider and mcp plugins expose OAuth token endpoints whose refresh_token grant authenticates only possession of the bound refreshToken row and matching client_id, without verifying the confidential client's client_secret, allowing an attacker with a valid refresh_token to mint access tokens and rotated refresh tokens through /api/auth/oauth2/token or /api/auth/mcp/token. The @better-auth/oauth-provider package is not affected. This issue is fixed in version 1.6.11."}],"affected":[{"vendor":"better-auth","product":"better-auth","versions":[{"version":"< 1.6.11","status":"affected"}]}],"references":[{"url":"https://github.com/better-auth/better-auth/security/advisories/GHSA-pw9m-5jxm-xr6h","name":"https://github.com/better-auth/better-auth/security/advisories/GHSA-pw9m-5jxm-xr6h","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/better-auth/better-auth/pull/9576","name":"https://github.com/better-auth/better-auth/pull/9576","tags":["x_refsource_MISC"]},{"url":"https://github.com/better-auth/better-auth/commit/1f2ff4215c4affff0b140b0c0a712c0dde35659c","name":"https://github.com/better-auth/better-auth/commit/1f2ff4215c4affff0b140b0c0a712c0dde35659c","tags":["x_refsource_MISC"]},{"url":"https://github.com/better-auth/better-auth/releases/tag/v1.6.11","name":"https://github.com/better-auth/better-auth/releases/tag/v1.6.11","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":9.1,"baseSeverity":"CRITICAL","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-287","lang":"en","description":"CWE-287: Improper Authentication","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-306","lang":"en","description":"CWE-306: Missing Authentication for Critical Function","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-345","lang":"en","description":"CWE-345: Insufficient Verification of Data Authenticity","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-863","lang":"en","description":"CWE-863: Incorrect Authorization","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-15T17:18:09.512Z"},"source":{"advisory":"GHSA-pw9m-5jxm-xr6h","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-18T01:07:56.612326Z","id":"CVE-2026-53512","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-18T01:08:08.419Z"}}]}}}