better-auth versions greater than 1.3.34 and before 1.4.0 contain a vulnerability in the multi-session plugin's /sign-out after-hook, which trusts… (CVE-2025-71402)
better-auth versions greater than 1.3.34 and before 1.4.0 have a vulnerability in the multi-session plugin's /sign-out after-hook. The vulnerability arises because the after-hook trusts raw multi-session cookies and forwards extracted values to internalAdapter.deleteSessions without verifying the cookie signature. This allows an attacker to supply a forged _multi-* cookie to delete arbitrary session tokens.
AI Analysis
Technical Summary
The vulnerability in better-auth affects versions >1.3.34 and <1.4.0 in the multi-session plugin's /sign-out after-hook. The code trusts raw multi-session cookies and forwards extracted values to internalAdapter.deleteSessions without verifying the cookie signature (e.g., via getSignedCookie). This lack of signature verification (CWE-347) enables an attacker to forge _multi-* cookies that trigger deletion of arbitrary session tokens, potentially disrupting user sessions.
Potential Impact
An attacker with the ability to supply forged multi-session cookies can cause deletion of arbitrary session tokens, potentially disrupting active user sessions. The severity is assessed as low, indicating limited impact or exploitability. There are no known exploits in the wild.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided at this time. Users should monitor vendor communications for updates and consider restricting access to the /sign-out endpoint or validating cookie signatures as a temporary mitigation if feasible.
better-auth versions greater than 1.3.34 and before 1.4.0 contain a vulnerability in the multi-session plugin's /sign-out after-hook, which trusts… (CVE-2025-71402)
Description
better-auth versions greater than 1.3.34 and before 1.4.0 have a vulnerability in the multi-session plugin's /sign-out after-hook. The vulnerability arises because the after-hook trusts raw multi-session cookies and forwards extracted values to internalAdapter.deleteSessions without verifying the cookie signature. This allows an attacker to supply a forged _multi-* cookie to delete arbitrary session tokens.
CVSS v4.0
Affected software
pkg:github/better-auth/better-authRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in better-auth affects versions >1.3.34 and <1.4.0 in the multi-session plugin's /sign-out after-hook. The code trusts raw multi-session cookies and forwards extracted values to internalAdapter.deleteSessions without verifying the cookie signature (e.g., via getSignedCookie). This lack of signature verification (CWE-347) enables an attacker to forge _multi-* cookies that trigger deletion of arbitrary session tokens, potentially disrupting user sessions.
Potential Impact
An attacker with the ability to supply forged multi-session cookies can cause deletion of arbitrary session tokens, potentially disrupting active user sessions. The severity is assessed as low, indicating limited impact or exploitability. There are no known exploits in the wild.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided at this time. Users should monitor vendor communications for updates and consider restricting access to the /sign-out endpoint or validating cookie signatures as a temporary mitigation if feasible.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-rf63-989x-x4x8
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2025-71402"]
- Ecosystems
- []
- Database Specific Severity
- LOW
- Cvss Version
- 4.0
Threat ID: 6a6e6299bf32cb7a344f9ee1
Added to database: 08/01/2026, 21:18:17 UTC
Last enriched: 08/01/2026, 21:25:25 UTC
Last updated: 08/01/2026, 22:22:48 UTC
Views: 3
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