Windows Telephony Service: Out-of-bounds read information disclosure
Summary
Microsoft fixed an out-of-bounds read (CWE-125) in the Windows Telephony Service that can disclose information from memory. An attacker needs local access and low privileges, and no user interaction is required. The issue is rated Important (CVSS 5.5) and no exploitation is known. The main concern is its use as a building block in a chain with other Telephony Service flaws fixed on the same day.
Affected
- Windows 10 Version 1607 and Windows Server 2016 (including Server Core): builds before 10.0.14393.9688
- Windows 10 Version 1809 and Windows Server 2019 (including Server Core): builds before 10.0.17763.9487
- Windows 10 Version 21H2: builds before 10.0.19044.7846
- Windows 10 Version 22H2: builds before 10.0.19045.7846
- Windows 11 Version 23H2: builds before 10.0.22631.7711
- Windows 11 Version 24H2: builds before 10.0.26100.9974
- Windows 11 Version 25H2: builds before 10.0.26200.9974
- Windows 11 Version 26H1: builds before 10.0.28000.3501
- Windows 11 Version 26H2: builds before 10.0.26300.9974
- Windows Server 2022: builds before 10.0.20348.5870
Verify exact builds on MSRC before deployment.
Fixed in
- November 2026 security update for each affected build. KB numbers: check the MSRC Security Update Guide.
- Unknown: whether the fixes for Windows 10 1607 and 1809 are delivered only through ESU.
Workaround
- Unknown. No vendor-documented workaround is known. Apply the security update.
Exploitation
- No exploitation in the wild is known.
- CISA SSVC: exploitation none. Rapid7 rates exploitation as less likely.
- No public proof-of-concept or researcher write-up was found.
Our recommendation
- Install the November 2026 cumulative update on all affected Windows clients and servers in the regular monthly cycle.
- Prioritise shared terminal servers, multi-user hosts and Windows 10 1607/1809 systems. Confirm ESU enrolment for the latter.
- Also deploy the other Telephony Service privilege-escalation fixes released the same day.
- Restrict local logon to trusted users.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Information disclosure – Windows Telephony Service
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less 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 Security Update Guide: CVE-2026-108408 msrc.microsoft.com
- CVE.org CVE Record: CVE-2026-108408 www.cve.org
- Rapid7: Patch Tuesday November 2026 www.rapid7.com
- Tenable: Microsoft November 2026 Patch Tuesday www.tenable.com
- Strix: CVE-2026-108408 (third-party, unverified versions) www.strix.ai
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, 16:56.
Original description (NVD)
Out-of-bounds read in Windows Telephony Service allows an authorized attacker to disclose information 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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