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8.6

Better Auth lets attackers sign in as other users

CVE-2026-110864 · published 6 days ago
Summary

The Better Auth software, versions from 1.5.0-beta.12 up to before 1.7.7, has a weakness in its OAuth Proxy feature that could let someone without credentials log in as another person. This could give an attacker access to private data and the ability to act on behalf of the victim. Update to the latest version of Better Auth as soon as possible to fix the issue.

What to do
  • Update better-auth better-auth to version 1.7.7 or later.
Affected software
VendorProductAffected versions
better-auth better-auth < 1.7.7
Original advisory text
Better Auth 1.5.0-beta.12 before 1.7.7 Authentication Bypass via OAuth Proxy
Better Auth from 1.5.0-beta.12 before 1.7.7 contains an authentication bypass vulnerability in the OAuth Proxy plugin that allows unauthenticated attackers to sign in as other users by forging encrypted profiles. When the proxy shares the global secret and cookie-stored state is used, attackers can obtain encrypted state for a fake profile with a victim's verified email to take over the account via implicit linking.
References
Fix within
Internet-facing 14 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit
  • Gives an attacker full control
Severity
8.6 High
Exploitation
<1% chance of attack within 30 days
Type
CWE-287Improper Authentication
Timeline
Published14 Oct 2026
Updated19 Oct 2026
First seen14 Oct 2026
Sources
CVE-2026-110864 · NVD
CVE-2026-110864 · MITRE
CVE-2026-110864 · OSV
GHSA-r4xp-prcw-77qf · GHSA
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