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CVE-2026-53517 better-auth CVE debrief

The CVE-2026-53517 vulnerability affects the Better Auth OAuth Provider, a high-severity issue with a CVSS score of 8.1. The vulnerability is caused by 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. This issue is fixed in version 1.6.11. Users should review system configurations and take necessary actions to protect their systems.

Vendor
better-auth
Product
Unknown
CVSS
HIGH 8.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-15
Original CVE updated
2026-07-21
Advisory published
2026-07-15
Advisory updated
2026-07-21

Who should care

Users of Better Auth OAuth Provider versions 1.4.8-beta.7 to 1.6.11 should be aware of this vulnerability and take necessary actions to protect their systems, including reviewing system configurations, validating oauthRefreshToken row sequences, and implementing compensating controls.

Technical summary

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. This allows concurrent requests with the same parent refresh token to pass the revoked check and create forked refresh-token families. The vulnerable range includes embedded better-auth plugin versions before 1.6.0. This issue is fixed in version 1.6.11. Users should review and validate oauthRefreshToken row sequences and implement compensating controls.

Defensive priority

High

Recommended defensive actions

  • Update to version 1.6.11 or later
  • Review and validate oauthRefreshToken row sequences
  • Implement compensating controls to prevent concurrent requests
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
  • Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
  • Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record was published on 2026-07-15T18:16:48.107Z and was last modified on 2026-07-21T16:00:22.173Z. The NVD entry is currently Analyzed. The vulnerability affects Better Auth OAuth Provider versions 1.4.8-beta.7 to 1.6.11. Users should review and validate oauthRefreshToken row sequences and implement compensating controls to prevent concurrent requests. Evidence limits suggest verifying system configurations and reviewing compensating controls.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-53517 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-53517

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-53517 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-53517

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.