CVE-2026-67336: critical vulnerability in better-auth
better-auth before 1.6.11 Insecure Cryptographic Defaults via oidcProvider
Published · Updated
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28Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 9.4epss 0.2%
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:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N
Affected products
better-auth · better-authRelated CVEs — better-auth
In the same product, most dangerous first.
CVE-2025-61928CRITICALBetter Auth: Unauthenticated API key creation through api-key pluginEPSS 19.7%CVE-2025-71404MEDIUMbetter-auth before 1.1.16 Reflected XSS via error parameterEPSS 0.7%CVE-2025-71399HIGHBetter Auth before 1.4.5 Path Normalization Bypass via rou3EPSS 0.5%CVE-2026-67337HIGHbetter-auth before 1.4.9 Two-Factor Authentication Bypass via session.cookieCacheEPSS 0.5%CVE-2025-71401CRITICALbetter-auth before 1.4.2 basePath Modification DoSEPSS 0.5%CVE-2026-67327HIGHbetter-auth before 1.6.22 Account Takeover via Magic-Link Email-OTPEPSS 0.4%