Skip to content
major vulnerability· requires attention

OS component vulnerability; widespread Windows deployments; network-based privilege escalation with potential disruption.

Systems

CVE-2026-20931

8.0
High
EPSS 0.86%Patch availableJan 14, 2026

External control of file name/path in Windows Telephony Service enables privilege escalation.

common questions

Is CVE-2026-20931 being exploited?

Not confirmed. CVE-2026-20931 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.86% probability of exploitation in the next 30 days.

How severe is CVE-2026-20931?

CVE-2026-20931 is rated High with a CVSS score of 8.0. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2026-20931?

Yes. A fix has been recorded for CVE-2026-20931. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2026-20931 affect?

CVE-2026-20931 affects Windows OS (Telephony Service). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

What should I do about CVE-2026-20931?

Patch OS when available; restrict Telephony Service exposure on networks.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

executive summary
technical analysis
affected
Windows OS (Telephony Service)
impact

Allows a network-adjacent attacker to escalate privileges by manipulating a file name/path in Telephony Service.

action required

Immediate action required

affected versions
Microsoft Windows 10 Version 1607
  • affected>= 10.0.14393.0 and < 10.0.14393.8783
Microsoft Windows 10 Version 1809
  • affected>= 10.0.17763.0 and < 10.0.17763.8276
Microsoft Windows 10 Version 21H2
  • affected>= 10.0.19044.0 and < 10.0.19044.6809
Microsoft Windows 10 Version 22H2
  • affected>= 10.0.19045.0 and < 10.0.19045.6809
Microsoft Windows 11 version 23H2
  • affected>= 10.0.22631.0 and < 10.0.22631.6491
Microsoft Windows 11 Version 23H2
  • affected>= 10.0.22631.0 and < 10.0.22631.6491
Microsoft Windows 11 Version 24H2
  • affected>= 10.0.26100.0 and < 10.0.26100.7623
Microsoft Windows 11 Version 25H2
  • affected>= 10.0.26200.0 and < 10.0.26200.7623
Microsoft Windows Server 2008 R2 Service Pack 1
  • affected>= 6.1.7601.0 and < 6.1.7601.28117
Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation)
  • affected>= 6.1.7601.0 and < 6.1.7601.28117
Microsoft Windows Server 2008 Service Pack 2
  • affected>= 6.0.6003.0 and < 6.0.6003.23717
Microsoft Windows Server 2008 Service Pack 2 (Server Core installation)
  • affected>= 6.0.6003.0 and < 6.0.6003.23717
Microsoft Windows Server 2012
  • affected>= 6.2.9200.0 and < 6.2.9200.25868
Microsoft Windows Server 2012 R2
  • affected>= 6.3.9600.0 and < 6.3.9600.22968
Microsoft Windows Server 2012 R2 (Server Core installation)
  • affected>= 6.3.9600.0 and < 6.3.9600.22968
Microsoft Windows Server 2012 (Server Core installation)
  • affected>= 6.2.9200.0 and < 6.2.9200.25868
Microsoft Windows Server 2016
  • affected>= 10.0.14393.0 and < 10.0.14393.8783
Microsoft Windows Server 2016 (Server Core installation)
  • affected>= 10.0.14393.0 and < 10.0.14393.8783
Microsoft Windows Server 2019
  • affected>= 10.0.17763.0 and < 10.0.17763.8276
Microsoft Windows Server 2019 (Server Core installation)
  • affected>= 10.0.17763.0 and < 10.0.17763.8276
Microsoft Windows Server 2022
  • affected>= 10.0.20348.0 and < 10.0.20348.4648
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation)
  • affected>= 10.0.25398.0 and < 10.0.25398.2092
Microsoft Windows Server 2025
  • affected>= 10.0.26100.0 and < 10.0.26100.32230
Microsoft Windows Server 2025 (Server Core installation)
  • affected>= 10.0.26100.0 and < 10.0.26100.32230

As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.

how to fix
Remediation steps are tailored for users whose stack is affected. Add this technology to your stack to see the fix checklist.
references
get alerted

Track only the vulnerabilities that affect your infrastructure.

start for free