Security Resilience

CVE-2026-21517

Microsoft Windows App ≤ 11.3.2

Published
10 February 2026
Modified
25 February 2026
Patch / advisory
View advisory
CVSS Score v3.1 4.7
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
EPSS Score 0.0038 31th percentile
Risk Priority 37 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-21517 is a medium-severity Link Following (CWE-59) vulnerability in Microsoft Windows App. Its CVSS base score is 4.7 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Escape to Host (T1611); ranked at the 31th 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.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access Control

EU & UK References

Vulnerability Data

Improper link resolution before file access ('link following') in Windows App for Mac allows an authorized attacker to elevate privileges locally.

CWE(s)
CWE-59

Related Threats

MITRE ATT&CK Enterprise Techniques

T1611 Escape to Host Privilege Escalation
Adversaries may break out of a container or virtualized environment to gain access to the underlying host.
attack.mitre.org →
T1034 Path Interception Persistence
**This technique has been deprecated.
attack.mitre.org →
T1014 Rootkit Stealth
Adversaries may use rootkits to hide the presence of programs, files, network connections, services, drivers, and other system components.
attack.mitre.org →
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.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-42834Same vendor: Microsoft
CVE-2024-43603Same vendor: Microsoft
CVE-2025-60710Same vendor: Microsoft
CVE-2023-35379Same vendor: Microsoft
CVE-2025-49738Same vendor: Microsoft
CVE-2025-55245Same vendor: Microsoft
CVE-2025-49739Same vendor: Microsoft
CVE-2025-25008Same vendor: Microsoft
CVE-2023-35347Same vendor: Microsoft
CVE-2023-21567Same vendor: Microsoft

Affected Assets

microsoft
windows app
≤ 11.3.2

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match

Proper enforcement of access authorizations on the resolved target resource stops a link from reaching an unintended object.

AC-6 Least Privilege partial match

Least-privilege limits the damage an attacker can cause after following an unintended link.

SI-10 Information Input Validation partial match

Validating file-name inputs can reject or canonicalize names that resolve to links before access occurs.

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.PS-06 mostly match
blocks

Secure SDLC practices directly require code to validate paths and avoid unsafe link following.

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 detect link-following flaws before release.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly address canonicalization and symlink attacks during implementation.

References