# CVE-2026-109346: better-auth device authorization UI misrepresentation in deviceAuthorization plugin

Source: https://junglewise.ai/threats/cve-2026-109346-better-auth-from-1-3-8-beta-3-before-1-7-0-rc-3-contains-a-ui  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-12. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-109346 · Severity: high · CVSS 8.1 · Published 2026-10-12

better-auth is an authentication library used to sign users into applications. A flaw in its optional device login feature omits critical information about which application is requesting access and what permissions it needs, allowing attackers to trick signed-in users into approving unauthorized device codes. Once approved, the attacker receives a live session token and can read or modify any data the user's account can access.

Technologies: [Better-Auth](https://junglewise.ai/threats/technologies/better-auth-better-auth), [better-auth (npm)](https://junglewise.ai/threats/technologies/better-auth). Vendors: [Better-Auth](https://junglewise.ai/threats/vendors/better-auth), [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-109346 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-109346 being exploited in the wild.

**How severe is CVE-2026-109346?** High severity, with a CVSS score of 8.1, published 12 October 2026.

**Which products and versions are affected?** Better-Auth 1.3.8-beta.3 before 1.7.0-rc.3; better-auth (npm) SEMVER:introduced=1.3.8-beta.3,fixed=1.7.0-rc.3.

**Is there a fix for CVE-2026-109346?** Yes. better-auth (npm): upgrade to 1.7.0-rc.3 or later. Until then: Disable the deviceAuthorization() plugin or block untrusted access to /device/code. If the plugin must remain enabled, configure a strict validateClient allowlist and build a custom approval endpoint that reads the pending request from trusted server-side storage, maps the client identifier to a display name, and shows the exact requested permissions before approval. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-109346 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-109346?** Check whether you run Better-Auth or better-auth (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- better-auth (npm): upgrade to 1.7.0-rc.3 or later

  ```sh
  npm install better-auth@1.7.0-rc.3
  ```


Disable the deviceAuthorization() plugin or block untrusted access to /device/code. If the plugin must remain enabled, configure a strict validateClient allowlist and build a custom approval endpoint that reads the pending request from trusted server-side storage, maps the client identifier to a display name, and shows the exact requested permissions before approval.

## Technical details

The deviceAuthorization plugin fails to return the requesting client_id and scope to the approval endpoint, preventing the UI from displaying which client initiated the flow. An attacker initiates a device code request via /device/code, and when a signed-in user approves the code without seeing the client details, the attacker redeems it at /device/token for a valid session token. This phishing attack requires user interaction to approve a code but requires no authentication or special privileges.

## Affected products

- better-auth better-auth 1.3.8-beta.3 before 1.7.0-rc.3

## Identifiers

- CVE-2026-109346
- GHSA-q84f-53jg-9ppm

## Timeline

- 2026-09-28: disclosed: GitHub Security Advisory GHSA-q84f-53jg-9ppm published
- 2026-10-12: advisory: CVE-2026-109346 published on NVD

## References

- [https://github.com/better-auth/better-auth/security/advisories/GHSA-q84f-53jg-9ppm](https://github.com/better-auth/better-auth/security/advisories/GHSA-q84f-53jg-9ppm)
- [https://www.vulncheck.com/advisories/better-auth-1.3.8-beta.3-before-1.7.0-rc.3-device-authorization-phishing-via-device](https://www.vulncheck.com/advisories/better-auth-1.3.8-beta.3-before-1.7.0-rc.3-device-authorization-phishing-via-device)

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