CVE-2026-45337: better auth Access Control Flaw — Fix

Description

Better Auth is an authentication and authorization library for TypeScript. From 1.6.0 until 1.6.11, the deviceAuthorization plugin treats any authenticated session as the owner of any pending device code because GET /device does not claim the row and POST /device/approve and POST /device/deny short-circuit when userId is unset, allowing an authenticated attacker who learns a valid user_code to bind the polling device to the attacker's account or deny the legitimate flow. This issue is fixed in version 1.6.11.

Is your site exposed to CVE-2026-45337?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

7.6

HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:L

EPSS — Exploit Prediction

0.0014

Probability of exploitation

0.04%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-285 CWE-285

CWE-345 CWE-345

Affected Products

Vendor	Product	Versions
better-auth	better_auth	1.6.0 — 1.6.11

References

Advisories & Patches

https://github.com/better-auth/better-auth/commit/99a254a79b59d5a3f5ca2123260118cddb5beed7 https://github.com/better-auth/better-auth/pull/9573 https://github.com/better-auth/better-auth/security/advisories/GHSA-cq3f-vc6p-68fh

Other References

https://github.com/better-auth/better-auth/releases/tag/v1.6.11

Frequently Asked Questions

What is CVE-2026-45337? +

Better Auth is an authentication and authorization library for TypeScript. From 1.6.0 until 1.6.11, the deviceAuthorization plugin treats any authenticated session as the owner of any pending device code because GET /device does not claim the row and POST /device/approve and POST /device/deny short-circuit when userId is unset, allowing an authenticated attacker who learns a valid user_code to bind the polling device to the attacker's account or deny the legitimate flow. This issue is fixed in version 1.6.11. It has a CVSS v3.1 base score of 7.6 (HIGH).

How severe is CVE-2026-45337? +

CVE-2026-45337 has a CVSS v3.1 score of 7.6 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0014, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-45337? +

CVE-2026-45337 affects products from better-auth, specifically: better_auth. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-45337? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-33398

NamelessMC is website software for Minecraft servers. In version 2.2.4, `modules/Forum/pages/forum/get_quotes.php` only checks whether the caller is logged in, then …

CVE-2025-3013

Insecure Direct Object References (IDOR) in access control in Customer Portal before 2.1.4 on NightWolf Penetration Testing allows an attacker …

CVE-2025-3014

Insecure Direct Object References (IDOR) in access control in Tracking 2.1.4 on NightWolf Penetration Testing allows an attacker to access …

CVE-2025-27509

fleetdm/fleet is an open source device management, built on osquery. In vulnerable versions of Fleet, an attacker could craft a …

CVE-2024-26291

An Unauthenticated Arbitrary File Read vulnerability affects the Agent when installed on a system. The parameter filename does not validate …

CVE-2025-49594

XWiki OIDC has various tools to manipulate OpenID Connect protocol in XWiki. Starting in version 2.17.1 and prior to version …

CVE-2026-45337