Microsoft Windows Telephony Service: Local privilege escalation
Summary
A local privilege escalation vulnerability in the Windows Telephony Service allows an authorized, low-privileged user to gain higher rights on the affected system. It is classified as missing authentication for a critical function (CWE-306). An attacker needs an existing local account or code execution on the machine, for example after phishing or opening a malicious file, to escalate to SYSTEM-level control. Microsoft fixed the issue in the November 2026 security update.
Affected
- Windows 10 Version 1607 (10.0.14393.0 before 10.0.14393.9688)
- Windows 10 Version 1809 (10.0.17763.0 before 10.0.17763.9487)
- Windows 10 Version 21H2 (10.0.19044.0 before 10.0.19044.7846)
- Windows 10 Version 22H2 (10.0.19045.0 before 10.0.19045.7846)
- Windows 11 Version 23H2 (10.0.22631.0 before 10.0.22631.7711)
- Windows 11 Version 24H2 (10.0.26100.0 before 10.0.26100.9974)
- Windows 11 Version 25H2 (10.0.26200.0 before 10.0.26200.9974)
- Windows 11 Version 26H1 (10.0.28000.0 before 10.0.28000.3501)
- Windows 11 Version 26H2 (10.0.26300.0 before 10.0.26300.9974)
- Windows Server 2016 incl. Server Core (10.0.14393.0 before 10.0.14393.9688)
- Windows Server 2019 incl. Server Core (10.0.17763.0 before 10.0.17763.9487)
- Windows Server 2022 (10.0.20348.0 before 10.0.20348.5870)
Fixed in
- November 2026 cumulative update for the respective Windows build (Patch Tuesday, 10 November 2026)
- Fixed build: the build numbers listed above or higher
- Unverified: KB 5131077 according to a third-party tracker; confirm on the MSRC page
Workaround
Unknown. No vendor workaround or third-party micropatch found. Installing the November 2026 update is the remedy.
Exploitation
- Public proof of concept: none found
- Exploited in the wild: unclear. Sources conflict on whether this CVE is the one flagged as exploited; check the MSRC Exploited flag
- Microsoft exploitability assessment: Exploitation More Likely (per Tenable)
- CISA SSVC: exploitation none, automatable no, technical impact total
Our recommendation
- Install the November 2026 cumulative update on all Windows workstations and servers in the normal Patch Tuesday cycle
- Prioritise shared workstations, RDS and terminal servers, and hosts where standard users could be targeted
- Check the MSRC Exploited flag for this CVE and treat it as urgent if it is marked
- Limit local user accounts and admin rights, and monitor for unexpected privilege changes on endpoints
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Telephony Service
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation more likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5131291, KB5131085, KB5131096, KB5131090, KB5131087, KB5132061
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- MSRC advisory CVE-2026-119886 msrc.microsoft.com
- CVE.org record CVE-2026-119886 www.cve.org
- Qualys Patch Tuesday review November 2026 blog.qualys.com
- Talos Patch Tuesday post November 2026 blog.talosintelligence.com
- Tenable November 2026 Patch Tuesday www.tenable.com
- Strix CVE-2026-119886 (third-party) www.strix.ai
- Trinetriops Patch Tuesday November 2026 (third-party) trinetriops.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 11 Nov 2026, 03:45.
Original description (NVD)
Missing authentication for critical function in Windows Telephony Service allows an authorized attacker to elevate privileges locally.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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