Cyber Resilience

CVE-2026-26123

Microsoft Authenticator ≤ 6.8.40

Published
10 March 2026
Modified
13 March 2026
Patch / advisory
View advisory
CVSS Score v3.1 5.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
EPSS Score 0.0060 46th percentile
Risk Priority 44 floored blend · peak EPSS

Summary

CVE-2026-26123 is a medium-severity Improper Authorization in Handler for Custom URL Scheme (CWE-939) vulnerability in Microsoft Authenticator. Its CVSS base score is 5.5 (Medium).

Operationally, ranked at the 46th 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-3 (Access Enforcement) and AC-6 (Least Privilege) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

Cwe is not in rca categories in Microsoft Authenticator allows an unauthorized attacker to disclose information locally.

CWE(s)
CWE-939NVD-CWE-noinfo

Related Threats

CVEs Like This One

CVE-2024-21390Same product: Microsoft Authenticator
CVE-2020-0986Same vendor: Microsoft
CVE-2024-29982Same vendor: Microsoft
CVE-2024-38228Same vendor: Microsoft
CVE-2025-21213Same vendor: Microsoft
CVE-2024-49011Same vendor: Microsoft
CVE-2024-43646Same vendor: Microsoft
CVE-2024-49039Same vendor: Microsoft
CVE-2024-21450Same vendor: Microsoft
CVE-2016-7193Same vendor: Microsoft

Affected Assets

microsoft
authenticator
≤ 6.8.40 · ≤ 6.2511.7533

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match

Access enforcement directly stops unauthorized actors from invoking the custom URL handler by requiring approved authorizations for that entry point.

AC-6 Least Privilege good match

Least privilege limits the authorizations granted to the handler, reducing the chance that any actor can invoke it without restriction.

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

Defining, enforcing, and reviewing access permissions directly addresses the missing authorization checks for custom URL scheme handlers.

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.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can discover missing authorization checks, but does not itself implement the required controls.

A.8.3 Information access restriction mostly match
prevents

Enforces explicit authorization checks on which actors may invoke handlers, directly addressing the missing restriction on custom-URL-scheme access.

A.5.15 Access control partial match
prevents

High-level access-control policy provides governance context but does not prescribe the technical authorization logic needed for URL-scheme handlers.

A.8.26 Application security requirements partial match
prevents

Requires security requirements that define which callers are permitted to trigger custom URL handlers, mitigating the authorization gap.

A.8.28 Secure coding partial match
prevents

Mandates secure coding practices that include proper authorization checks before executing actions triggered by custom URL schemes.

References