EUVD-2026-56630
GHSA-2qpg-2679-q8m8
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local attack vector with low-privilege requirement is consistent with a TAPI service LPE; full CIA impact reflects achievable SYSTEM-level code execution; no scope change as the service does not cross security boundaries.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Use after free in Windows Telephony Service allows an authorized attacker to elevate privileges locally.
AnalysisAI
Privilege escalation via use-after-free in the Windows Telephony Service (TAPI) allows a locally authenticated, low-privileged attacker to gain SYSTEM-level access across a broad range of Windows desktop and server releases. The vulnerability affects Windows 10, Windows 11 (all current feature releases), and Windows Server 2012 through 2025, representing near-universal coverage of supported and legacy Microsoft platforms. No public exploit identified at time of analysis; vendor-released patches are available via Microsoft Update.
Technical ContextAI
The Windows Telephony Service implements the Telephony Application Programming Interface (TAPI), a built-in Windows subsystem providing voice, data, and fax communication abstractions for applications. CWE-416 (Use After Free) arises when heap memory is deallocated but one or more pointers to that region remain accessible; subsequent access to or writes into the freed region can corrupt allocator metadata or adjacent objects, enabling attackers to redirect control flow. In a privilege escalation context within a Windows service process, this typically results in arbitrary code execution under the service's security context, often SYSTEM. The CVSS vector AV:L/AC:L/PR:L confirms the attack is local, requires no special preparation, and needs only a standard user account, consistent with a kernel or service-mode memory corruption primitive.
RemediationAI
Apply the Microsoft security updates that bring affected builds to the fixed versions listed above, distributed via Windows Update, WSUS, or Microsoft Update Catalog. The advisory is available at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62701. For systems where patching cannot occur immediately, a compensating control is to restrict interactive and remote logon rights to the affected hosts, reducing the pool of accounts capable of reaching the local attack surface - however, this does not eliminate risk for multi-user or terminal-server environments. Disabling the Windows Telephony Service (TapiSrv) is a potential workaround but will break any TAPI-dependent applications (fax, modem, VoIP clients); evaluate application dependencies before disabling. Legacy systems (Server 2012, Server 2012 R2) require enrollment in Microsoft's Extended Security Updates program to receive patches. Vendor-released patch: per-platform build numbers confirmed above.
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Same weakness CWE-416 – Use After Free
View allSame technique Denial Of Service
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External POC / Exploit Code
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