CVE-2026-67336
better-auth before 1.6.11 Insecure Cryptographic Defaults via oidcProvider
CRITICAL 9.4
At a glance
- Source
- NVD
- EPSS
- EPSS 0.24 % · percentile 15 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- VulnCheck
- NVD status
- Deferred
Description
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.
Weaknesses (CWE)
- CWE-327 — Use of a Broken or Risky Cryptographic Algorithm
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | CRITICAL 9.4 | 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 | VulnCheck |
| CVSS 3.1 | HIGH 8.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N | VulnCheck |
| CVSS 4.0 | CRITICAL 9.4 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X | NVD · disclosure@vulncheck.com (Secondary) |
| CVSS 3.1 | HIGH 8.7 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N | NVD · disclosure@vulncheck.com (Secondary) |
Advisories
- GHSA-9h47-pqcx-hjr4 — Better Auth has insecure cryptographic defaults in oidcProvider: alg=none advertised and plain PKCE accepted by default
European references
- ENISA EUVD · EUVD-2026-51816
- GCVE · GCVE-0-2026-67336
Affected products
| Product | Versions |
|---|---|
| better-auth · better-auth | affected 0 < 1.6.11 ; unaffected 1.6.11 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |