CVE-2026-67336 — HIGH (8.7)

Vulnerability Description

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 Score

8.7

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

CHANGED

Confidentiality

HIGH

Integrity

HIGH

Availability

NONE

Related Weaknesses (CWE)

CWE-327

References

FAQ

What is CVE-2026-67336?

CVE-2026-67336 is a vulnerability with a CVSS score of 8.7 (HIGH). 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...

How severe is CVE-2026-67336?

CVE-2026-67336 has been rated HIGH with a CVSS base score of 8.7/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-67336?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.