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9.1

Better Auth allows login as another user via crafted link

CVE-2026-114607 · published 16 days ago
Summary

The Better Auth library for TypeScript can treat an OAuth sign‑in state value as a Magic Link token when certain configuration options are used. This lets an attacker start an OAuth login for a known email address and then use the returned state to sign in as that user without accessing their email. Update to version 1.7.7 or adjust the settings to stop using plain or hashed tokens for Magic Links.

What to do

The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.

Affected software
VendorProductAffected versions
better-auth better-auth >= 1.4.0-beta.18, < 1.7.7
Original advisory text
better-auth: OAuth state can be used as a Magic Link to sign in as another user
Better Auth is an authentication and authorization library for TypeScript. From 1.4.0-beta.18 until 1.7.7, deployments that enable Magic Link with storeToken set to plain, or with storeToken set to hashed and the global verification.storeIdentifier setting also set to hashed, enable a built-in social or Generic OAuth provider, and use account.storeStateStrategy set to database can accept an OAuth sign-in state value as a Magic Link token. These settings can cause Magic Link verification records and OAuth state to resolve to the same stored identifier, allowing an unauthenticated attacker to start OAuth sign-in for a known email address and redeem the returned state through Magic Link without controlling the mailbox or completing the provider callback. The attacker can obtain a normal session for an existing user, or create an account incorrectly marked as email verified when sign-up is enabled. This issue is fixed in version 1.7.7.
References
Fix within
Internet-facing 3 days
Internal 60 days
  • Not known to be exploited
  • Can be exploited automatically
  • Gives an attacker full control
Severity
9.1 Critical
Exploitation
<1% chance of attack within 30 days
Type
CWE-287Improper Authentication
Timeline
Published22 Oct 2026
Updated4 Nov 2026
First seen22 Oct 2026
Sources
CVE-2026-114607 · NVD
CVE-2026-114607 · MITRE
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