CVE-2026-67336
better-auth versions before 1.6.11 contain insecure cryptographic defaults in the oidcProvider and mcp plugins that advertise the none algorithm and accept plain PKCE by default. Attackers can exploit algorithm negotiation to accept unsigned tokens or intercept authorization codes when PKCE plain is used instead of the required S256 method.
Published:Aug 1, 2026
Last Modified:Aug 3, 2026
EPS:Aug 1, 2026
EPSS Score:0.00159
CVSS Score:8.7
Affected Products
Vendor
Product
Action
Vendor
Better-auth
Product
Better-auth\/oauth-provider
Better-auth
Better-auth\/oauth-provider
Exploits
No exploit reference
Common Weakness Enumeration
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Vulnerability Scoring System
Attack Vector
Network
Adjacent
Local
Physical
Privileges Required
None
Low
High
User Interaction
None
Required
Scope
Unchanged
Changed
Confidentiality
None
Low
High
Integrity
None
Low
High
Availability
None
Low
High
