Get a Demo

Let's Patch It!

Book a short call with one our specialists, we'll walk you through how Endor Patches work, and ask you a few questions about your environment (like your primary programming languages and repository management). We'll also send you an email right after you fill out the form, feel free to reply with any questions you have in advance!

CVE

CVE-2026-53512

Better Auth: OAuth refresh-token replay via missing client authentication on oidc-provider and mcp plugins
Back to all
CVE

CVE-2026-53512

Better Auth: OAuth refresh-token replay via missing client authentication on oidc-provider and mcp plugins

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 refreshtoken grant authenticates only possession of the bound refreshToken row and matching clientid, without verifying the confidential client's clientsecret, allowing an attacker with a valid refreshtoken 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.

Package Versions Affected

Package Version
patch Availability
No items found.

Automatically patch vulnerabilities without upgrading

Fix Without Upgrading
Detect compatible fix
Apply safe remediation
Fix with a single pull request

CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
9.1
-
4.0
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/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
C
H
U
0
-
C
H
U
9.1
-
3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Related Resources

No items found.

References

https://github.com/better-auth/better-auth/releases/tag/v1.6.11, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53512.json, https://github.com/better-auth/better-auth/security/advisories/GHSA-pw9m-5jxm-xr6h, https://nvd.nist.gov/vuln/detail/CVE-2026-53512, https://github.com/better-auth/better-auth/commit/1f2ff4215c4affff0b140b0c0a712c0dde35659c, https://github.com/better-auth/better-auth/pull/9576

Severity

0

CVSS Score
0
10

Basic Information

Base CVSS
0
EPSS Probability
0.00275%
EPSS Percentile
0.18113%
Introduced Version
0
Fix Available
1f2ff4215c4affff0b140b0c0a712c0dde35659c

Fix Critical Vulnerabilities Instantly

Secure your app without upgrading.
Fix Without Upgrading