Cyber Resilience

CVE-2026-45337

Access Control in Better-Auth Better Auth 1.6.0 – 1.6.11

Published
15 July 2026
Modified
21 July 2026
Patch / advisory
CVSS Score v3.1 7.6
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:L
EPSS Score 0.0014 4th percentile
Risk Priority 53 floored blend · peak EPSS

Summary

CVE-2026-45337 is a high-severity Improper Authorization (CWE-285) vulnerability in Better-Auth Better Auth. Its CVSS base score is 7.6 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Mark-of-the-Web Bypass (T1553.005); ranked at the 4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-24 (Access Control Decisions) and AC-25 (Reference Monitor) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1553.005 Mark-of-the-Web Bypass Defense Impairment
Adversaries may abuse specific file formats to subvert Mark-of-the-Web (MOTW) controls.
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
T1195 Supply Chain Compromise Initial Access
Adversaries may manipulate products or product delivery mechanisms prior to receipt by a final consumer for the purpose of data or system compromise.
T1195.001 Compromise Software Dependencies and Development Tools Initial Access
Adversaries may manipulate software dependencies and development tools prior to receipt by a final consumer for the purpose of data or system compromise.
T1195.002 Compromise Software Supply Chain Initial Access
Adversaries may manipulate application software prior to receipt by a final consumer for the purpose of data or system compromise.
T1542.002 Component Firmware Stealth
Adversaries may modify component firmware to persist on systems.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-53516Same product: Better-Auth Better Auth
CVE-2026-53514Same product: Better-Auth Better Auth
CVE-2026-53512Same product: Better-Auth Better Auth
CVE-2024-56734Same product: Better-Auth Better Auth
CVE-2025-27143Same product: Better-Auth Better Auth
CVE-2026-53515Same product: Better-Auth Better Auth
CVE-2026-53513Same product: Better-Auth Better Auth
CVE-2026-53517Same product: Better-Auth Better Auth
CVE-2026-53518Same product: Better-Auth Better Auth
CVE-2026-41427Same vendor: Better-Auth

Affected Assets

better-auth
better auth
1.6.0 — 1.6.11

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)
  • 14 hardening rules · 5 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V3.5.5

Mitigating Controls (NIST 800-53 r5) AI

Mandates that access-control decisions are made and applied to each request before access occurs.

Requires a tamperproof, always-invoked reference monitor that performs authorization checks.

Directly requires enforcement of approved authorizations for every access request, stopping improper or missing checks.

Explicit requirement to protect session authenticity structurally prevents the weakness for communications.

Limits granted privileges so that even a bypassed check affects fewer resources.

Integrity verification tools detect (but do not stop) the acceptance of data lacking authenticity.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-05 mostly match
prevents

PR.AA-05 mostly prevents CWE-285 via enforced policy, reviews, and least-privilege authorization decisions, yet CWE-285 remains only partially prevented because code-level check omissions or errors can still occur outside that single control.

PR.PS-06 mostly match
prevents

Secure SDLC practices catch and eliminate most authorization defects before release, yet a single broad outcome cannot address every design, role, and runtime facet of CWE-285.

RC.RP-05 mostly match
degrades

CWE-345 directly impairs RC.RP-05's verification of restored-asset integrity/authenticity, largely defeating the outcome while still leaving other restoration-confirmation steps partially viable.

PR.AA-01 partial match
prevents

PR.AA-01 supplies managed identities and access-request workflows that can support downstream authorization decisions, yet does nothing to enforce or verify authorization checks inside a product, leaving CWE-285 fully unaddressed by this control alone.

PR.IR-01 partial match
prevents

Network segmentation/zero-trust limits external reachability (partial prevention of exploitation) but leaves application-level authorization logic untouched, so the CWE remains fully introducible and only one facet of its risk is addressed.

PR.PS-05 none match
prevents

PR.PS-05 blocks unauthorized binaries/DNS while CWE-285 is an in-product authorization-check defect, so the control neither prevents the weakness nor removes any of its risk.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

finds

Security testing can detect missing or weak data authenticity verification.

prevents

Granular, policy-driven assignment of permissions and dynamic enforcement of those permissions prevent the incorrect or missing authorization decisions that lead to improper authorization flaws.

prevents

By requiring documented authorization rules and periodic policy reviews, the control makes it less likely that authorization decisions will be omitted or implemented inconsistently across applications.

prevents

Mapping access rights to information classification and business requirements forces correct enforcement of authorization decisions, blocking the incorrect authorization weakness at the policy and implementation stage.

finds

Independent reviewers evaluate whether authorization logic matches policy, thereby reducing the window in which incorrect or missing authorization checks remain in production.

finds

By requiring managers to verify that authorization decisions match policy and to remediate deviations, the control limits the persistence of incorrect or missing authorization checks.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (4 rules)
  • V-248574 YUM must be configured to prevent the installation of patches, service packs, device drivers, or OL 8 system components that have not been digitally signed using a certificate that is recognized and approved by the organization. prevents CWE-345
  • V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
  • V-252656 The OL 8 operating system must not be configured to bypass password requirements for privilege escalation. prevents CWE-285
Oracle Linux 9 (1 rule)
  • V-271525 OL 9 must have GPG signature verification enabled for all software repositories. prevents CWE-345
RHEL 7 (5 rules)
  • V-204447 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
  • V-204448 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
  • V-204429 The Red Hat Enterprise Linux operating system must be configured so that users must provide a password for privilege escalation. prevents CWE-285
RHEL 8 (3 rules)
  • V-230264 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
  • V-230265 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
  • V-251712 The RHEL 8 operating system must not be configured to bypass password requirements for privilege escalation. prevents CWE-285
RHEL 9 (1 rule)
  • V-257822 RHEL 9 must have GPG signature verification enabled for all software repositories. prevents CWE-345

References