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. A
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.
Details
Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-67336
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-67336 | coverage & exploitation status | NVD · CVE.org |
Recent advisories for better-auth
A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.
- mediumCVE-2026-67337: better-auth versions before 1.4.9 contain a two-factor authentication bypass vulnerability whe…nvd · 2026-08-01
- mediumCVE-2026-67335: better-auth versions before 1.6.2 fail to validate the OAuth state parameter against the store…nvd · 2026-08-01
- lowCVE-2026-67334: better-auth versions before 1.6.11 fail to delete cached sessions when removing users via admi…nvd · 2026-08-01
- highCVE-2026-67333: better-auth before 1.6.13 (and pre-release builds 1.7.0-beta.0 through 1.7.0-beta.3) fail to v…nvd · 2026-08-01
- mediumCVE-2026-67332: @better-auth/oauth-provider before 1.7.0-beta.4 fails to bind access-token audience to the aut…nvd · 2026-08-01
- highCVE-2026-67331: better-auth SCIM versions from 1.5.0 before 1.7.0-beta.4 fail to bind non-organization SCIM pr…nvd · 2026-08-01
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