CVSS 4.0
9.4 criticalCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:NCVE-2026-67336
Critical (9.4). EPSS 0.2% chance of exploitation in the next 30 days. Fixed in better-auth 1.6.11.
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.
Severity
CVSS 3.1
8.7 highCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N- EPSS
- 0.2% chance of exploitation in the next 30 days; higher than 14% of CVEs (scores of 2026-10-31)
- CWE
- CWE-327
- Published
- Modified
- Record from
- the NVD, synced
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-9h47-pqcx-hjr4 | npm | better-auth | <1.6.11 | 1.6.11 |