Vulnerability · Published Aug 25, 2026 · Assigned by VulnCheck
CVE-2026-80192better-auth SSO before 1.6.27 Domain Ownership Authentication Bypass
High 8.1
In plain English
A high-severity improper authentication in sso from better-auth. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities).
Official description
@better-auth/sso before 1.6.27 (and before 1.4.8 in the 1.4.x line and before 1.7.0-rc.5 in the 1.7 prerelease line) contains two domain-ownership flaws. When domain verification is disabled, automatic organization assignment accepts unverified provider domains, allowing an authenticated organization owner/administrator to register an SSO provider for an arbitrary domain and have users with matching email domains added to the attacker's organization with default member permissions. When domain verification is enabled, a race condition between the verify-domain and update-provider endpoints can apply completed DNS proof to a different domain; combined with implicit account linking, this can link an attacker-controlled identity provider to an existing user account. Exploitation requires the SSO plugin (and, for the org-assignment path, the organization plugin) with the relevant configuration enabled.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| better-auth | sso | 1.4.8-beta.1 – before 1.4.8 |
| better-auth | sso | 1.4.9 – before 1.6.27 |
| better-auth | sso | 1.7.0-beta.0 – before 1.7.0-rc.5 |
Weakness: CWE-287 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
References
- GitHub Security Advisory (GHSA-8c5h-wx78-2cfg) vendor-advisory
- VulnCheck Advisory: better-auth SSO before 1.6.27 Domain Ownership Authentication Bypass third-party-advisory