{"cve":"CVE-2026-67336","nvd":{"published":"2026-08-01T13:17:04.557","modified":"2026-09-08T20:34:34.997","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.","cvss_v4":{"vector":"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","score":9.4},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N","score":8.7},"cwes":["CWE-327"],"references":["https://github.com/better-auth/better-auth/security/advisories/GHSA-9h47-pqcx-hjr4","https://www.vulncheck.com/advisories/better-auth-before-insecure-cryptographic-defaults-via-oidcprovider"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:47:10.050265369+00:00"},"epss":{"cve":"CVE-2026-67336","score":0.00236,"percentile":0.14674,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-9h47-pqcx-hjr4","url":"https://osv.dev/vulnerability/GHSA-9h47-pqcx-hjr4","summary":"Better Auth has insecure cryptographic defaults in oidcProvider: alg=none advertised and plain PKCE accepted by default","modified":"2026-08-02T03:56:48.208414323Z","packages":[{"ecosystem":"npm","name":"better-auth","purl":"pkg:npm/better-auth","ranges":["<1.6.11"],"fixed":["1.6.11"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}