CVE-2026-53512
Better Auth auth bypass: refresh tokens can mint access tokens without client_secret.
Is CVE-2026-53512 being exploited?
Not confirmed. CVE-2026-53512 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.27% probability of exploitation in the next 30 days.
How severe is CVE-2026-53512?
CVE-2026-53512 is rated Critical with a CVSS score of 9.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-53512?
Yes. A fix has been recorded for CVE-2026-53512. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-53512 affect?
CVE-2026-53512 affects Better Auth (TypeScript) legacy oidcProvider plugin <=1.6.10, Better Auth legacy mcp plugin <=1.6.10, Endpoints: /api/auth/oauth2/token, /api/auth/mcp/token, @better-auth/oauth-provider (not affected). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-53512?
Upgrade Better Auth to >=1.6.11 and rotate affected refresh_tokens immediately.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
An attacker with a valid refresh_token can obtain new access tokens and rotated refresh_tokens via legacy endpoints without client_secret.
Immediate action required
- affected< 1.6.11
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.