CVE-2026-109346 — better-auth 1.3.8-beta.3 before 1.7.0-rc.3 Device Authorization Phishing via /device
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.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.3% (30-day exploitation probability)+3
- Technical severity (high)+6
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Better-auth Better-auth).
- The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Exploitation requires user interaction: tighten email/web filtering and warn affected users.
- Search available logs for exploit probes, errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Better-auth | Better-auth | ≥ 1.3.8-beta.3 and < 1.7.0-rc.3 | Vulnerable | CVE Program (cve.org) e CISA ADP |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 8.5 | CVSS 4.0 | High | — | — | disclosure@vulncheck.com via NIST National Vulnerability Database |
| 8.5 | CVSS 4.0 | High | — | — | VulnCheck via CVE Program (cve.org) e CISA ADP |
| 8.1 | CVSS 3.1 | High | 2.8 | 5.2 | disclosure@vulncheck.com via NIST National Vulnerability Database |
| 8.1 | CVSS 3.1 | High | — | — | VulnCheck via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N (score shown at the top: disclosure@vulncheck.com) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.28%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · better-auth/better-auth
- Record published
- CVSS changed · 8.1
- Source status changed · → Received
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
2 on the record
Elsewhere on this site
Related CVEs (same products)
- Low CVE-2026-110861 Better Auth drizzle-adapter 1.6.17 before 1.7.7 Rate Limit Bypass via Race Condition 18h
- Critical CVE-2026-110862 Better Auth 1.4.0-beta.18 before 1.7.7 Authentication Bypass via Magic Link 18h
- High CVE-2026-110864 Better Auth 1.5.0-beta.12 before 1.7.7 Authentication Bypass via OAuth Proxy 18h
- Medium CVE-2025-71401 better-auth before 1.4.2 basePath Modification DoS Aug 2, 2026
- High CVE-2025-71399 Better Auth before 1.4.5 Path Normalization Bypass via rou3 Aug 2, 2026
- Low CVE-2026-67334 better-auth Stale Sessions Persist After User Deletion Aug 1, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No CISA SSVC assessment.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-109346 is "better-auth 1.3.8-beta.3 before 1.7.0-rc.3 Device Authorization Phishing via /device", rated High. It affects Better-auth (Better-auth); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.1 describes technical severity. EPSS 0.28% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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