better-auth: User Interface (UI) Misrepresentation of Critical Information
CVE-2026-109346 is a high-severity user interface (UI) misrepresentation of critical information vulnerability in better-auth, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version 1.7.0-rc.3 as the first without the flaw, so updating better-auth to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.28% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update better-auth to 1.7.0-rc.3 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Better-auth | better-auth | 1.3.8-beta.3 up to, but not including, 1.7.0-rc.3 | 1.7.0-rc.3 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N. Scored by CNA (vulncheck.com).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 8.5 | High | CNA (vulncheck.com) |
| CVSS 3.1 | 8.1 | High | CNA (vulncheck.com) |
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: User Interface (UI) Misrepresentation of Critical Information
The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks.
How developers prevent this class of flaw
- Perform data validation (e.g. syntax, length, etc.) before interpreting the data.
- Create a strategy for presenting information, and plan for how to display unusual characters.
More User Interface (UI) Misrepresentation of Critical Information vulnerabilities (CWE-451)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in better-auth
- 9.1 Critical severity
- 9.1 Critical severity
- 7.4 High severity
- 9.1 Critical severity
- 8.6 High severity
- 8.7 High severity
Recent User Interface (UI) Misrepresentation of Critical Information vulnerabilities
- 7.4 High severity
- 7.4 High severity
- 8.1 High severity
- 7.5 High severity
- 8.0 High severity
- 8.8 High severity
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