CVE-2026-80192

better-auth SSO before 1.6.27 Domain Ownership Authentication Bypass

Published Aug 25, 2026 CVSS 4.0 · 8.6 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Better-auth sso
Vendors & Products Better-auth sso
Type Values Removed Values Added
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.
Title better-auth SSO before 1.6.27 Domain Ownership Authentication Bypass
First Time appeared Better-auth
Better-auth better-auth\/sso
Weaknesses CWE-287
CPEs cpe:2.3:a:better-auth:better-auth\/sso:*:*:*:*:*:*:*:*
cpe:2.3:a:better-auth:better-auth\/sso:-:*:*:*:*:*:*:*
Vendors & Products Better-auth
Better-auth better-auth\/sso
References
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N'}

cvssV4_0

{'score': 8.6, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Oct 8, 2026, 3:25 PM
Reserved
Aug 25, 2026, 11:14 PM
Status
Deferred
Published
Aug 26, 2026, 5:18 AM
Modified
Oct 8, 2026, 4:17 PM