{"id":"CVE-2026-53518","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-53518","generatedAt":"2026-10-28T09:27:04.010Z","title":"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…","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.","published":"2026-07-15T18:16:48.000Z","lastModified":"2026-07-21T16:03:12.000Z","status":"Analyzed","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"4.0","score":7.6,"severity":"HIGH","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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-362","CWE-367"],"affected":["better-auth/better-auth\\/oauth-provider","better-auth/better auth"],"epss":{"score":0.00409,"percentile":0.34986,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.41%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://github.com/better-auth/better-auth/commit/b4bc65a007784b2eb0efb459e5fa6fd8055d3ec9","tags":["Patch"],"source":"security-advisories@github.com"},{"url":"https://github.com/better-auth/better-auth/releases/tag/v1.6.11","tags":["Release Notes"],"source":"security-advisories@github.com"},{"url":"https://github.com/better-auth/better-auth/security/advisories/GHSA-7w99-5wm4-3g79","tags":["Mitigation","Vendor Advisory"],"source":"security-advisories@github.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-53518","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}