CVE-2026-67336
Auth library allowed unsigned tokens and weak PKCE, enabling token forgery and code interception.
Is CVE-2026-67336 being exploited?
Not confirmed. CVE-2026-67336 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.16% probability of exploitation in the next 30 days.
How severe is CVE-2026-67336?
CVE-2026-67336 is rated Critical with a CVSS score of 9.4. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-67336?
Yes. A fix has been recorded for CVE-2026-67336. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-67336 affect?
CVE-2026-67336 affects better-auth <1.6.11, better-auth oidcProvider plugin, better-auth mcp plugin, OpenID Connect deployments using better-auth. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-67336?
Upgrade to better-auth >=1.6.11, disable 'none' alg, enforce PKCE S256
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attackers can accept unsigned JWTs (alg=none) to forge tokens and intercept/steal auth codes when PKCE plain is used.
Immediate action required
- affected< 1.6.11
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.