CVE-2020-1123 — Connected User Experiences and Telemetry Service Denial of Service Vulnerability

Executive Summary

A denial of service vulnerability exists when Connected User Experiences and Telemetry Service improperly handles file operations. An attacker who successfully exploited this vulnerability could cause a system to stop responding. To exploit the vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerability. The security update addresses the vulnerability by correcting how the Connected User Experiences and Telemetry Service handles file operations.

Overview

5.5

CVSS MEDIUM

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Denial of Service

Released May 12 2020

Last Updated May 12 2020

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.00923 — 0.55652 percentile

NVD CVSS 5.5 MEDIUM — matches MSRC

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

CONFIDENTIALITY

None

INTEGRITY

None

AVAILABILITY

High

EXPLOIT CODE MATURITY

Proof-of-Concept

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 5.0

EPSS Score

0.00923

probability of exploitation in the next 30 days

0.55652 percentile - updated 2026-06-21

View on FIRST.org

Affected Products

26 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 for 32-bit Systems	`4556826 (Security Update)`	Important	Denial of Service	Yes
Windows 10 for x64-based Systems	`4556826 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1607 for 32-bit Systems	`4556813 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1607 for x64-based Systems	`4556813 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1709 for 32-bit Systems	`4556812 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1709 for ARM64-based Systems	`4556812 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1709 for x64-based Systems	`4556812 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1803 for 32-bit Systems	`4556807 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1803 for ARM64-based Systems	`4556807 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1803 for x64-based Systems	`4556807 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1809 for 32-bit Systems	`4551853 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1809 for ARM64-based Systems	`4551853 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1809 for x64-based Systems	`4551853 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1903 for 32-bit Systems	`4556799 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1903 for ARM64-based Systems	`4556799 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1903 for x64-based Systems	`4556799 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1909 for 32-bit Systems	`4556799 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1909 for ARM64-based Systems	`4556799 (Security Update)`	Important	Denial of Service	Yes
Windows 10 Version 1909 for x64-based Systems	`4556799 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2016	`4556813 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2016 (Server Core installation)	`4556813 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2019	`4551853 (Security Update)`	Important	Denial of Service	Yes
Windows Server 2019 (Server Core installation)	`4551853 (Security Update)`	Important	Denial of Service	Yes
Windows Server, version 1803 (Server Core Installation)	`4556807 (Security Update)`	Important	Denial of Service	Yes
Windows Server, version 1903 (Server Core installation)	`4556799 (Security Update)`	Important	Denial of Service	Yes
Windows Server, version 1909 (Server Core installation)	`4556799 (Security Update)`	Important	Denial of Service	Yes

Patches

6 patches

Article	Type	Restart
`4556826`	Security Update	Yes
`4556813`	Security Update	Yes
`4556812`	Security Update	Yes
`4556807`	Security Update	Yes
`4551853`	Security Update	Yes
`4556799`	Security Update	Yes

Known Exploits

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

Conor McErlane, Gábor Selján ( @GaborSeljan ), @edwardzpeng

References

MSRC Advisory MITRE NVD