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CVE-2026-110863— Better Auth @better-auth/sso before 1.7.3 Authentication Bypass via Personal SSO Providers

Quick assessment

Affected
better-auth sso
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Better Auth 的 模块从版本 1.7.0-rc.2 到 1.7.3 存在一个身份验证绕过漏洞。攻击者可以通过注册个人 SSO（单点登录）提供商，以其他用户的身份登录系统。具体而言，攻击者可以复制合法提供商的 OIDC（OpenID Connect）发行者标识符或 SAML 实体标识符，并断言受害者的 subject（主体标识）或 NameID。由于账户查找过程忽略了 providerId（提供商标识），系统会为受害者的账户创建会话，从而实现身份冒充。

CVSS 8.1 · High EPSS 0.27% · P18

Affected Version Matrix 1

VendorProduct Version RangeStatus
better-auth sso 1.7.0-rc.2< 1.7.3 affected
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I. Basic Information for CVE-2026-110863

Vulnerability Information
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Vulnerability Title
Better Auth @better-auth/sso before 1.7.3 Authentication Bypass via Personal SSO Providers
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
认证机制不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
better-auth sso 1.7.0-rc.2 ~ 1.7.3 -

II. Public POCs for CVE-2026-110863

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III. Intelligence Information for CVE-2026-110863

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Other References for CVE-2026-110863 (2)

Same Patch Batch · better-auth · 2026-10-14 · 4 CVEs total

CVE-2026-110862 9.1 CRITICAL Better Auth 1.4.0-beta.18 before 1.7.7 Authentication Bypass via Magic Link
CVE-2026-110864 7.4 HIGH Better Auth 1.5.0-beta.12 before 1.7.7 Authentication Bypass via OAuth Proxy
CVE-2026-110861 3.7 LOW Better Auth drizzle-adapter 1.6.17 before 1.7.7 Rate Limit Bypass via Race Condition

IV. Related Vulnerabilities

Same product: sso
Same vendor: better-auth
Same weakness: CWE-287

V. Comments for CVE-2026-110863

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