---
id: CVE-2026-110863
title: >-
  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
summary: >-
  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 p…
severity: high
cvss: 8.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N'
cwe:
  - CWE-287
vendor: better-auth
product: sso
affected:
  - sso >= 1.7.0-rc.2 < 1.7.3
published: '2026-10-14'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T18:17:34.130'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-110863'
references:
  - url: >-
      https://github.com/better-auth/better-auth/security/advisories/GHSA-mx9r-x6ww-qjw9
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/better-auth-better-auth-sso-before-1.7.3-authentication-bypass-via-personal-sso-providers
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
epss: 0.00269
epssPercentile: 0.18946
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T16:35:48.861225Z'
ingestedAt: '2026-10-15T00:02:07.186Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.