CVE-2020-1108: A denial of service vulnerability exists when .NET Core or .NET Framework improperly handles web requests

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HIGH 7.5REMOTEWATCHLISTDOWNGRADEUPGRADEDOWNGRADE

CVE-2020-1108 is a high-severity flaw (CVSS 7.5) affecting .net, .net core, .net framework. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A denial of service vulnerability exists when .NET Core or .NET Framework improperly handles web requests. An attacker who successfully exploited this vulnerability could cause a denial of service against a .NET Core or .NET Framework web application. The vulnerability can be exploited remotely, without authentication. A remote unauthenticated attacker could exploit this vulnerability by issuing specially crafted requests to the .NET Core or .NET

Why this priority

High severity
EPSS top 6%: very likely to be exploited
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	6.5% (top 6%)
CISA exploited list	No
Published	2020-05-21
Last modified	2026-08-19

Publisher (CNA): Microsoft Corporation · Vendor: microsoft

Last updated 2026-08-19 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-05-21 23:15 UTCPublished CVE record published
2026-08-19 17:17 UTCUpdated Record last modified

microsoft .net DOWNGRADE

Affected: 5.0 preview1 · 5.0 preview2 · 5.0 preview3

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.0

1. Check installed version

apt-cache policy .net || rpm -q .net || .net --version

2. No fixed release: DOWNGRADE to a release before 5.0 (Debian / Ubuntu)

apt-cache madison .net sudo apt install .net=<VERSION_BEFORE_5.0> sudo apt-mark hold .net

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list .net sudo dnf downgrade .net-<VERSION_BEFORE_5.0> sudo dnf versionlock add .net

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

microsoft .net core UPGRADE

Affected: >= 2.1 and <= 2.1.18 · >= 3.0 and <= 3.1.4 · 2.1 · 3.1

Fixed in: newer than 3.1.4

Safe to downgrade to: a release before 2.1

1. Check installed version

apt-cache policy .net-core || rpm -q .net-core || .net-core --version

2. UPGRADE to newer than 3.1.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade .net-core

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade .net-core

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.1 (Debian / Ubuntu)

apt-cache madison .net-core sudo apt install .net-core=<VERSION_BEFORE_2.1> sudo apt-mark hold .net-core

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list .net-core sudo dnf downgrade .net-core-<VERSION_BEFORE_2.1> sudo dnf versionlock add .net-core

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

microsoft .net framework DOWNGRADE

Affected: 2.0 sp2 · 3.0 sp2 · 4.6 · 3.5 · 4.5.2 · 4.6.1 · 4.6.2 · 4.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0

1. Check installed version

apt-cache policy .net-framework || rpm -q .net-framework || .net-framework --version

2. No fixed release: DOWNGRADE to a release before 2.0 (Debian / Ubuntu)

apt-cache madison .net-framework sudo apt install .net-framework=<VERSION_BEFORE_2.0> sudo apt-mark hold .net-framework

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list .net-framework sudo dnf downgrade .net-framework-<VERSION_BEFORE_2.0> sudo dnf versionlock add .net-framework

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

microsoft visual studio 2017 DOWNGRADE

Affected: 15.9

Fixed in: no fixed release known

Safe to downgrade to: a release before 15.9

1. Check installed version

apt-cache policy visual-studio-2017 || rpm -q visual-studio-2017 || visual-studio-2017 --version

2. No fixed release: DOWNGRADE to a release before 15.9 (Debian / Ubuntu)

apt-cache madison visual-studio-2017 sudo apt install visual-studio-2017=<VERSION_BEFORE_15.9> sudo apt-mark hold visual-studio-2017

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list visual-studio-2017 sudo dnf downgrade visual-studio-2017-<VERSION_BEFORE_15.9> sudo dnf versionlock add visual-studio-2017

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

microsoft visual studio 2019 DOWNGRADE

Affected: 16.0 · 16.4 · 16.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 16.0

1. Check installed version

apt-cache policy visual-studio-2019 || rpm -q visual-studio-2019 || visual-studio-2019 --version

2. No fixed release: DOWNGRADE to a release before 16.0 (Debian / Ubuntu)

apt-cache madison visual-studio-2019 sudo apt install visual-studio-2019=<VERSION_BEFORE_16.0> sudo apt-mark hold visual-studio-2019

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list visual-studio-2019 sudo dnf downgrade visual-studio-2019-<VERSION_BEFORE_16.0> sudo dnf versionlock add visual-studio-2019

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

microsoft powershell DOWNGRADE

Affected: 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0

1. Check installed version

apt-cache policy powershell || rpm -q powershell || powershell --version

2. No fixed release: DOWNGRADE to a release before 7.0 (Debian / Ubuntu)

apt-cache madison powershell sudo apt install powershell=<VERSION_BEFORE_7.0> sudo apt-mark hold powershell

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list powershell sudo dnf downgrade powershell-<VERSION_BEFORE_7.0> sudo dnf versionlock add powershell

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-1108?

.net: downgrade or apply the listed mitigation; .net core: upgrade to newer than 3.1.4; .net framework: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-1108 being exploited?

CVE-2020-1108 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-1108 affect?

CVE-2020-1108 affects .net, .net core, .net framework. Severity is high (CVSS 7.5). A denial of service vulnerability exists when .NET Core or .NET Framework improperly handles web requests. An attacker who successfully exploited this vulnerability could cause a denial of service against a .NET Core or .NET Framework web a

How urgent is CVE-2020-1108?

Priority 60/100. High severity; EPSS top 6%: very likely to be exploited; Remotely exploitable, no login, no user action; On your watchlist

Software pages

.NET vulnerabilities · Visual Studio vulnerabilities · PowerShell vulnerabilities

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References

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