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.

CVSS v3 8.7 HIGH

8.7^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.2 / Impact : 5.8

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/better-auth/better-auth/security/advisories/GHSA-9h47-pqcx-hjr4
https://www.vulncheck.com/advisories/better-auth-before-insecure-cryptographic-defaults-via-oidcprovider

Configurations

No configuration.

History

01 Aug 2026, 13:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-08-01 13:17

Updated : 2026-08-01 13:17

NVD link : CVE-2026-67336

Mitre link : CVE-2026-67336

CVE.ORG link : CVE-2026-67336

JSON object : View

Products Affected

No product.

CWE

CWE-327

Use of a Broken or Risky Cryptographic Algorithm

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