Cyber Resilience

CVE-2026-34338

High

Published: 12 May 2026

Published
12 May 2026
Modified
14 May 2026
KEV Added
Patch
CVSS Score v3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0005 15.7th percentile
Risk Priority 16 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-34338 is a high-severity Use After Free (CWE-416) vulnerability in Microsoft Windows 10 21H2. Its CVSS base score is 7.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 15.7th 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 Telephony Service allows an authorized attacker to elevate privileges locally.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
Why these techniques?

UAF vulnerability in Windows service directly enables local privilege escalation via exploitation of a software flaw.

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

CVEs Like This One

CVE-2026-27916Same 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
CVE-2026-33098Same product: Microsoft Windows 10 1607
CVE-2026-20822Same 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.

addresses: CWE-416

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

References