{"id":"CVE-2026-53518","state":"PUBLISHED","title":"Better Auth OAuth Provider: Race Condition in Authorization Code Exchange Enables Multi-Use Code Redemption","description":"Better Auth is an authentication and authorization library for TypeScript. From 1.6.0 until 1.6.11, the @better-auth/oauth-provider POST /oauth2/token endpoint for the authorization_code grant redeems a single-use authorization code through a non-atomic find-then-delete sequence, allowing two concurrent requests to pass the read step and mint independent access tokens, refresh tokens, and ID tokens; legacy /oauth2/token and /mcp/token paths in oidc-provider and mcp plugins share the same primitive. This issue is fixed in version 1.6.11.","publishedAt":"2026-07-15T17:17:06.410Z","updatedAt":"2026-07-15T18:07:49.190Z","severity":{"score":7.6,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/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":">= 1.6.0, < 1.6.11","status":"affected"}]}],"references":["https://github.com/better-auth/better-auth/security/advisories/GHSA-7w99-5wm4-3g79","https://github.com/better-auth/better-auth/commit/b4bc65a007784b2eb0efb459e5fa6fd8055d3ec9","https://github.com/better-auth/better-auth/releases/tag/v1.6.11"],"weaknesses":["CWE-362","CWE-367"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/53xxx/CVE-2026-53518.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53518","state":"PUBLISHED","datePublished":"2026-07-15T17:17:06.410Z","dateUpdated":"2026-07-15T18:07:49.190Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-09T17:30:33.456Z"},"containers":{"cna":{"title":"Better Auth OAuth Provider: Race Condition in Authorization Code Exchange Enables Multi-Use Code Redemption","descriptions":[{"lang":"en","value":"Better Auth is an authentication and authorization library for TypeScript. From 1.6.0 until 1.6.11, the @better-auth/oauth-provider POST /oauth2/token endpoint for the authorization_code grant redeems a single-use authorization code through a non-atomic find-then-delete sequence, allowing two concurrent requests to pass the read step and mint independent access tokens, refresh tokens, and ID tokens; legacy /oauth2/token and /mcp/token paths in oidc-provider and mcp plugins share the same primitive. This issue is fixed in version 1.6.11."}],"affected":[{"vendor":"better-auth","product":"better-auth","versions":[{"version":">= 1.6.0, < 1.6.11","status":"affected"}]}],"references":[{"url":"https://github.com/better-auth/better-auth/security/advisories/GHSA-7w99-5wm4-3g79","name":"https://github.com/better-auth/better-auth/security/advisories/GHSA-7w99-5wm4-3g79","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/better-auth/better-auth/commit/b4bc65a007784b2eb0efb459e5fa6fd8055d3ec9","name":"https://github.com/better-auth/better-auth/commit/b4bc65a007784b2eb0efb459e5fa6fd8055d3ec9","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":"PASSIVE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":7.6,"baseSeverity":"HIGH","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-362","lang":"en","description":"CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-367","lang":"en","description":"CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-15T17:17:06.410Z"},"source":{"advisory":"GHSA-7w99-5wm4-3g79","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-15T18:07:40.302581Z","id":"CVE-2026-53518","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-15T18:07:49.190Z"}}]}}}