Vulnerability in Better-Auth
CVE-2026-109346
better-auth from 1.3.8-beta.3 before 1.7.0-rc.3 contains a UI misrepresentation vulnerability in the deviceAuthorization plugin because GET /device omits the requesting client_id and scope. Attackers can start a device request via /device/code, trick signed-in users into approving the code, then redeem it at /device/token for a live session token.
Published .
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/better-auth/better-auth/security/advisories/GHSA-q84f-53jg-9ppm (vendor-advisory)
- www.vulncheck.com/advisories/better-auth-1.3.8-beta.3-before-1.7.0-rc.3-device-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-109346?
- CVE-2026-109346 is a high-severity vulnerability in Better-Auth, classified under User Interface (UI) Misrepresentation of Critical Information. CVSS score: 8.1/10. Published 2026-10-12.
- How severe is CVE-2026-109346?
- High severity. CVSS v3 base score is 8.1 out of 10.