Better Auth @better-auth/sso from 1.7.0-rc.2 before 1.7.3 contains an authentication bypass vulnerability that allows authenticated users to sign in as other users by registering a personal SSO provider. Attackers can copy a legitimate provider's OIDC issuer or SAML entity ID and assert a victim's subject or NameID, because account lookup ignores providerId, creating sessions for victim accounts.

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact High

Vulnerable System Integrity Impact High

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
better-auth sso unaffected
Version Status Constraints
1.7.0-rc.2 affected < 1.7.3

No data.

No data.

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Project Subscriptions

Vendors Products
Better-auth Subscribe
Better-auth\/sso Subscribe
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/better-auth/better-auth/security/advisories/GHSA-mx9r-x6ww-qjw9 cve-icon cve-icon
https://www.vulncheck.com/advisories/better-auth-better-auth-sso-before-1.7.3-authentication-bypass-via-personal-sso-providers cve-icon cve-icon
History

Wed, 14 Oct 2026 23:00:00 +0000

Type Values Removed Values Added
Description Better Auth @better-auth/sso from 1.7.0-rc.2 before 1.7.3 contains an authentication bypass vulnerability that allows authenticated users to sign in as other users by registering a personal SSO provider. Attackers can copy a legitimate provider's OIDC issuer or SAML entity ID and assert a victim's subject or NameID, because account lookup ignores providerId, creating sessions for victim accounts.
Title Better Auth @better-auth/sso before 1.7.3 Authentication Bypass via Personal SSO Providers
First Time appeared Better-auth
Better-auth better-auth\/sso
Weaknesses CWE-287
CPEs 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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-10-14T22:52:50.378Z

Reserved: 2026-10-14T22:18:33.239Z

Link: CVE-2026-110863

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-14T23:17:27.830

Modified: 2026-10-14T23:17:27.830

Link: CVE-2026-110863

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses