CVE-2025-71402

Low

Description

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 raw multi-session cookies and forwards extracted values to internalAdapter.deleteSessions without verifying the cookie signature (e.g., via getSignedCookie). An attacker can supply a forged _multi-* cookie to trigger deletion of arbitrary session tokens.

SeverityLow

CVSS2.0

Exploit probability—

ProductBetter-auth

PublishedAug 1, 2026

First seenAug 1, 2026

Weakness typeCWE-347CWE-347

How to fix

Update

better-auth1.4.0 or later

Vendor advisories

github.com/better-auth/better-auth/security/advisories/GHSA-wmjr-v86c-m9jj

Affected products

Product	Affected versions	Fixed in
better-authnpm	1.3.34 ≤ v < 1.4.0	1.4.0

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