---
cve: "CVE-2026-53512"
severity: "CRITICAL"
cvss: 9.1
epss: "21%"
vendor: "better-auth"
kev: false
exploited: false
published: "2026-07-15 18:16:47"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-13T07:35:35+02:00"
---

# CVE-2026-53512

> 9.1 CRITICAL · 🧪 PoC

## Beschreibung

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.

## CVSS-Vektor

```
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
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- f41514ef07cfafc5dbf463bd1500aee6575d88a7 (Commit)
- 1f2ff4215c4affff0b140b0c0a712c0dde35659c (Commit)

## Referenzen

- <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>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-53512) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_