Cyber Resilience

CVE-2026-40406

High

Published: 12 May 2026

Published
12 May 2026
Modified
15 May 2026
KEV Added
—
Patch
—
CVSS Score v3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS Score 0.0008 24.7th percentile
Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-40406 is a high-severity Use After Free (CWE-416) vulnerability in Microsoft Windows 10 21H2. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Credential Access (T1212); ranked at the 24.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

Use after free in Windows TCP/IP allows an unauthorized attacker to disclose information over a network.

CWE(s)
CWE-416

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
attack.mitre.org →
Why these techniques?

Remote unauthenticated use-after-free in the TCP/IP stack directly enables exploitation for information disclosure (T1212) and remote retrieval of local system data (T1005).

Confidence: MEDIUM · MITRE ATT&CK Enterprise v18.1

CVEs Like This One

CVE-2026-34338Same product: Microsoft Windows 10 1607
CVE-2026-27916Same product: Microsoft Windows 10 1607
CVE-2026-23669Same product: Microsoft Windows 10 1607
CVE-2026-40382Same product: Microsoft Windows 10 1607
CVE-2026-27923Same product: Microsoft Windows 10 1607
CVE-2026-32156Same product: Microsoft Windows 10 1607
CVE-2026-27915Same product: Microsoft Windows 10 1607
CVE-2026-40408Same product: Microsoft Windows 10 1607
CVE-2026-24289Same product: Microsoft Windows 10 1607
CVE-2026-27909Same product: Microsoft Windows 10 1607

Affected Assets

microsoft
windows 10 1607
≤ 10.0.14393.9140 · ≤ 10.0.14393.9140
microsoft
windows 10 1809
≤ 10.0.17763.8755 · ≤ 10.0.17763.8755
microsoft
windows 10 21h2
≤ 10.0.19044.7291 · ≤ 10.0.19044.7291 · ≤ 10.0.19044.7291
microsoft
windows 10 22h2
≤ 10.0.19045.7291 · ≤ 10.0.19045.7291 · ≤ 10.0.19045.7291
microsoft
windows 11 23h2
≤ 10.0.22631.7079 · ≤ 10.0.22631.7079
microsoft
windows 11 24h2
≤ 10.0.26100.8390 · ≤ 10.0.26100.8390
microsoft
windows 11 25h2
≤ 10.0.26200.8390 · ≤ 10.0.26200.8390
microsoft
windows 11 26h1
≤ 10.0.28000.2113 · ≤ 10.0.28000.2113
microsoft
windows server 2012
all versions, r2
microsoft
windows server 2016
≤ 10.0.14393.9140
+4 more product configuration(s) — see NVD for full list

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-16 Memory Protection
addresses: CWE-416

Use-after-free exploits that achieve arbitrary code execution are blocked or significantly hardened by non-executable pages and ASLR.

References