CVE-2026-53518
Better Auth OAuth Provider: Race Condition in Authorization Code Exchange Enables Multi-Use Code Redemption
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 4.0 | High7.6 | 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 |
| NVDNVD · Analyzed | 4.0 | High7.6 | 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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
- EPSS (exploitation in 30 days)
- 0.41% · top 65% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.6.
Weakness
Affected products
- affected >= 1.6.0, < 1.6.11
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- npm@better-auth/oauth-providerGHSA-7w99-5wm4-3g79 (opens in a new tab)
- npmbetter-authGHSA-7w99-5wm4-3g79 (opens in a new tab)
References (3)
- https://github.com/better-auth/better-auth/security/advisories/GHSA-7w99-5wm4-3g79 (opens in a new tab)x_refsource_CONFIRM
- https://github.com/better-auth/better-auth/commit/b4bc65a007784b2eb0efb459e5fa6fd8055d3ec9 (opens in a new tab)x_refsource_MISC
- https://github.com/better-auth/better-auth/releases/tag/v1.6.11 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-7w99-5wm4-3g79 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-53518)Record last updated .