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.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-287",
"CWE-306",
"CWE-345",
"CWE-863"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53512.json"
}{
"cpe": "cpe:2.3:a:better-auth:better_auth:*:*:*:*:*:node.js:*:*",
"extracted_events": [
{
"introduced": "0"
},
{
"fixed": "1.6.11"
}
],
"source": [
"CPE_RANGE",
"REFERENCES"
]
}