CVE-2026-67336: better-auth before 1.6.11 Insecure Cryptographic Defaults via oidcProvider

Published Aug 1, 2026
·
Updated

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.

Affected Software

1 affected component
better-auth<1.6.11

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade better-auth to a version that resolves this vulnerability.

    Fixed in 1.6.11
  2. Upgrade

    Upgrade better-auth/oidcProvider to a version that resolves this vulnerability.

    Fixed in 1.6.11
  3. Upgrade

    Upgrade better-auth/mcp to a version that resolves this vulnerability.

    Fixed in 1.6.11

Event History

Aug 1, 2026
CVE Published
via MITRE·12:22 PM
Data Sourced
via MITRE·12:22 PM
DescriptionSeverityWeakness
Data Sourced
via NVD·01:17 PM
DescriptionSeverityWeakness
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