CVE-2026-25188: Windows Telephony Service Elevation of Privilege Vulnerability

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-10 · updated 2026-06-19
Weakness: CWE-122

Description

Heap-based buffer overflow in Windows Telephony Service allows an unauthorized attacker to elevate privileges over an adjacent network.

Affected products

Microsoft Windows 10 1607: before 10.0.14393.8957 — fixed in 10.0.14393.8957
Microsoft Windows 10: before 10.0.17763.8511 — fixed in 10.0.17763.8511
Microsoft Windows 10: before 10.0.19044.7058 — fixed in 10.0.19044.7058
Microsoft Windows 10: before 10.0.19045.7058 — fixed in 10.0.19045.7058
Microsoft Windows 11: before 10.0.22631.6783 — fixed in 10.0.22631.6783
Microsoft Windows 11: before 10.0.26100.7979 — fixed in 10.0.26100.7979
Microsoft Windows 11 25H2: before 10.0.26200.7979 — fixed in 10.0.26200.7979
Microsoft Windows 11 version 26H1: before 10.0.28000.1719 — fixed in 10.0.28000.1719
Microsoft Windows Server 2012: r2
Microsoft Windows Server 2016: before 10.0.14393.8957 — fixed in 10.0.14393.8957
Microsoft Windows Server 2019: before 10.0.17763.8511 — fixed in 10.0.17763.8511
Microsoft Windows Server 2022: before 10.0.20348.4830 — fixed in 10.0.20348.4830
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): before 10.0.25398.2207 — fixed in 10.0.25398.2207
Microsoft Windows Server 2025: before 10.0.26100.32463 — fixed in 10.0.26100.32463
Microsoft Windows 10 1607: from 10.0.14393.0 before 10.0.14393.8957 — fixed in 10.0.14393.8957
Microsoft Windows 10: from 10.0.17763.0 before 10.0.17763.8511 — fixed in 10.0.17763.8511
Microsoft Windows 10: from 10.0.19044.0 before 10.0.19044.7058 — fixed in 10.0.19044.7058
Microsoft Windows 10: from 10.0.19045.0 before 10.0.19045.7058 — fixed in 10.0.19045.7058
Microsoft Windows 11 version 22H3: from 10.0.22631.0 before 10.0.22631.6783 — fixed in 10.0.22631.6783
Microsoft Windows 11: from 10.0.22631.0 before 10.0.22631.6783 — fixed in 10.0.22631.6783
Microsoft Windows 11: from 10.0.26100.0 before 10.0.26100.8037 — fixed in 10.0.26100.8037
Microsoft Windows 11 25H2: from 10.0.26200.0 before 10.0.26200.8037 — fixed in 10.0.26200.8037
Microsoft Windows 11 version 26H1: from 10.0.28000.0 before 10.0.28000.1719 — fixed in 10.0.28000.1719
Microsoft Windows Server 2012: from 6.2.9200.0 before 6.2.9200.25973 — fixed in 6.2.9200.25973
Microsoft Windows Server 2012 R2: from 6.3.9600.0 before 6.3.9600.23074 — fixed in 6.3.9600.23074
Microsoft Windows Server 2016: from 10.0.14393.0 before 10.0.14393.8957 — fixed in 10.0.14393.8957
Microsoft Windows Server 2019: from 10.0.17763.0 before 10.0.17763.8511 — fixed in 10.0.17763.8511
Microsoft Windows Server 2022: from 10.0.20348.0 before 10.0.20348.4893 — fixed in 10.0.20348.4893
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): from 10.0.25398.0 before 10.0.25398.2207 — fixed in 10.0.25398.2207
Microsoft Windows Server 2025: from 10.0.26100.0 before 10.0.26100.32522 — fixed in 10.0.26100.32522

How to fix

Upgrade to a fixed version: Microsoft Windows 10 1607 10.0.14393.8957; Microsoft Windows 10 10.0.17763.8511; Microsoft Windows 10 10.0.19044.7058; Microsoft Windows 10 10.0.19045.7058; Microsoft Windows 11 10.0.22631.6783; Microsoft Windows 11 10.0.26100.7979; Microsoft Windows 11 25H2 10.0.26200.7979; Microsoft Windows 11 version 26H1 10.0.28000.1719; Microsoft Windows Server 2016 10.0.14393.8957; Microsoft Windows Server 2019 10.0.17763.8511; Microsoft Windows Server 2022 10.0.20348.4830; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.2207. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-25188

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