8.7High
CVE-2026-67336better-auth before 1.6.11 Insecure Cryptographic Defaults via oidcProvider
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.
Weakness (CWE):
CWE-327
Data: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Published as the sources state it, in English.
Affected products and versions
| Vendor | Product | Versions | |
|---|---|---|---|
| better-auth | better-auth | < 1.6.11, fixed 1.6.11 | |
| better-auth | better-auth/oauth-provider | < 1.6.11 |
References and patches
- GitHub Security Advisory (GHSA-9h47-pqcx-hjr4) vendor-advisory
- VulnCheck Advisory: better-auth before 1.6.11 Insecure Cryptographic Defaults via oidcProvider third-party-advisory