Strix
26.1K

CVE-2026-53517

HIGHCVSS 8.1/10EPSS 0.41%

Last modified

CVE-2026-53517 is a high-severity vulnerability rated 8.1/10 on the CVSS scale. Better Auth is an authentication and authorization library for TypeScript. From 1.4.8-beta.7 until 1.6.11, the @better-auth/oauth-provider POST /oauth2/token endpoint on the refresh_token grant performs a non-atomic read, validate, revoke, and mint sequence on the oauthRefreshToken row, allowing concurrent requests with the same parent refresh token to pass the revoked check and create forked refresh-token families; the vulnerable range also includes embedded better-auth plugin versions before 1.6.0. EPSS estimates a 0.41% chance of exploitation in the next 30 days.

Description

Better Auth is an authentication and authorization library for TypeScript. From 1.4.8-beta.7 until 1.6.11, the @better-auth/oauth-provider POST /oauth2/token endpoint on the refresh_token grant performs a non-atomic read, validate, revoke, and mint sequence on the oauthRefreshToken row, allowing concurrent requests with the same parent refresh token to pass the revoked check and create forked refresh-token families; the vulnerable range also includes embedded better-auth plugin versions before 1.6.0. This issue is fixed in version 1.6.11.

Metrics

CVSS 3.1
8.1/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS Probability
0.41%

33.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
Better-AuthBetter-Auth\/Oauth-Provider>= 1.6.0, < 1.6.11
Better-AuthBetter Auth>= 1.4.9, < 1.6.11
Better-AuthBetter Auth1.4.8

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-53517?
Better Auth is an authentication and authorization library for TypeScript. From 1.4.8-beta.7 until 1.6.11, the @better-auth/oauth-provider POST /oauth2/token endpoint on the refresh_token grant performs a non-atomic read, validate, revoke, and mint sequence on the oauthRefreshToken row, allowing concurrent requests with the same parent refresh token to pass the revoked check and create forked refresh-token families; the vulnerable range also includes embedded better-auth plugin versions before 1.6.0. This issue is fixed in version 1.6.11.
How severe is CVE-2026-53517?
CVE-2026-53517 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 0.41% probability of exploitation in the next 30 days.
How do I fix CVE-2026-53517?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

Related CVEs from 2026

View all 2026CVEs →

Are you affected by CVE-2026-53517?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST