{"cve":"CVE-2026-53518","nvd":{"published":"2026-07-15T18:16:48.240","modified":"2026-07-21T16:03:12.347","status":"Analyzed","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.","cvss_v4":{"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","score":7.6},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","score":8.1},"cwes":["CWE-362","CWE-367"],"references":["https://github.com/better-auth/better-auth/commit/b4bc65a007784b2eb0efb459e5fa6fd8055d3ec9","https://github.com/better-auth/better-auth/releases/tag/v1.6.11","https://github.com/better-auth/better-auth/security/advisories/GHSA-7w99-5wm4-3g79"],"products":["better-auth:better-auth\\/oauth-provider","better-auth:better_auth"],"source":"nvd","synced_at":"2026-10-19T22:45:36.895656543+00:00"},"epss":{"cve":"CVE-2026-53518","score":0.00409,"percentile":0.35191,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-7w99-5wm4-3g79","url":"https://osv.dev/vulnerability/GHSA-7w99-5wm4-3g79","summary":"@better-auth/oauth-provider's OAuth authorization-code grant allows concurrent redemption when two token requests race the find-then-delete primitive","modified":"2026-07-20T19:30:24.125273382Z","packages":[{"ecosystem":"npm","name":"@better-auth/oauth-provider","purl":"pkg:npm/%40better-auth/oauth-provider","ranges":[">=1.6.0 <1.6.11"],"fixed":["1.6.11"]},{"ecosystem":"npm","name":"better-auth","purl":"pkg:npm/better-auth","ranges":["<1.6.11"],"fixed":["1.6.11"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}