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Microsoft Windows

CVE-2020-1118 — Microsoft Windows Transport Layer Security Denial of Service Vulnerability

Important CVSS 7.5 EPSS 0.1613 2020-05 archive

Executive Summary

A denial of service vulnerability exists in the Windows implementation of Transport Layer Security (TLS) when it improperly handles certain key exchanges. An attacker who successfully exploited the vulnerability could cause a target system to stop responding. To exploit this vulnerability, a remote unauthenticated attacker could send a specially crafted request to a target system utilizing TLS 1.2 or lower, triggering the system to automatically reboot. The update addresses the vulnerability by changing the way TLS key exchange messages are validated.

Overview

7.5
CVSS HIGH
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 0.1613 — 0.96516 percentile
NVD CVSS 7.5 HIGH — differs from MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C
ATTACK VECTOR
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
None
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: 7.7

EPSS Score

0.1613
probability of exploitation in the next 30 days
0.96516 percentile - updated 2026-06-21
View on FIRST.org

Affected Products

20 affected products
Product KB Article Severity Impact Restart Required
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 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

4 patches
Article Type Restart
4556812 Security Update Yes
4556807 Security Update Yes
4551853 Security Update Yes
4556799 Security Update Yes

Known Exploits

Acknowledgments

None

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