PT-2025-62896 · Unknown · Better Auth

Mufeedvh · CVE-2025-71402 · Published 2025-11-26 · Updated 2026-08-01

Positive Technologies (AI Summary)

CVSS v3.1

9.6

Critical

Base vector

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

Name of the Vulnerable Software and Affected Versions better-auth versions 1.3.35 through 1.3.99

Description The multi-session plugin contains a flaw in the /sign-out endpoint after-hook. The system trusts raw multi-session cookies and forwards extracted values to the deleteSessions() function within the internalAdapter without verifying the cookie signature, such as by using getSignedCookie(). This allows an attacker to provide a forged multi-* cookie to trigger the deletion of arbitrary session tokens.

Recommendations Update better-auth to version 1.4.0 or later. As a temporary mitigation, restrict the use of the multi-session plugin until the update is applied.

Exploit

Fix

Improper Verification of Cryptographic Signature

Insufficient Verification of Data Authenticity

Improper Authentication

Weakness Enumeration

CWE-347

CWE-345

CWE-287

Related Identifiers

CVE-2025-71402

GHSA-WMJR-V86C-M9JJ

Affected Products

Better Auth

References · 9

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/71xxx/CVE-2025-71402.json · Exploit
• https://github.com/better-auth/better-auth/security/advisories/GHSA-wmjr-v86c-m9jj · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2025-71402 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2025-71402 · Security Note
• 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://vulncheck.com/advisories/better-auth-before-session-revocation-via-forged-cookie · Note