PT-2025-49391 · Npm · Better Auth

Published 2025-11-26 · Updated 2025-11-26

OSV

CVSS v3.1

9.6

Critical

Base vector

AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H

Summary

A vulnerability was identified in the multi-session plugin for Better Auth, specifically in the /sign-out after-hook. The hook trusts raw multi-session cookies and forwards the extracted values directly to internalAdapter.deleteSessions without verifying the cookie signature. Because cookie values are not validated with getSignedCookie (or any equivalent check), an attacker can supply a forged multi-* cookie to trigger deletion of arbitrary session tokens.

Fix

Improper Authentication

Insufficient Verification of Data Authenticity

Weakness Enumeration

CWE-287

CWE-345

Related Identifiers

GHSA-WMJR-V86C-M9JJ

Affected Products

Better Auth

References · 5

• https://osv.dev/vulnerability/GHSA-wmjr-v86c-m9jj · Vendor Advisory
• https://github.com/better-auth/better-auth · Note
• https://github.com/better-auth/better-auth/releases/tag/v1.4.0 · Note
• https://github.com/better-auth/better-auth/commit/cfc453a2a6eb02951f9a0a7c944064936e73eee8 · Note
• https://github.com/better-auth/better-auth/security/advisories/GHSA-wmjr-v86c-m9jj · Note