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CVE-2021-24112: .NET Core Remote Code Execution Vulnerability

61
This week
HIGH 8.1REMOTEWATCHLISTUPGRADEUPGRADEUPGRADE

CVE-2021-24112 is a high-severity flaw (CVSS 8.1) affecting .net, .net core, mono. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

.NET Core Remote Code Execution Vulnerability

Why this priority

  • High severity
  • Remotely exploitable, no login, no user action
  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score8.1 (High)
Attack vectorNetwork (remote)
Attack complexityHigh
Privileges neededNone
User interactionNone
EPSS exploit chance3.5% (top 11%)
CISA exploited listNo
WeaknessCWE-94
Published2021-02-25
Last modified2026-10-07
Publisher (CNA): Microsoft Corporation · Vendor: microsoft

Share: LinkedIn · X · Reddit

Last updated 2026-10-07 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

microsoft .net UPGRADE
Affected: >= 5.0 and <= 5.0.2
Fixed in: newer than 5.0.2
Safe to downgrade to: a release before 5.0
1. Check installed version
apt-cache policy .net || rpm -q .net || .net --version
2. UPGRADE to newer than 5.0.2 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade .net
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade .net
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 5.0 (Debian / Ubuntu)
apt-cache madison .net sudo apt install .net=<VERSION_BEFORE_5.0> sudo apt-mark hold .net
3. If no update is available yet, 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 <= 2.1.24 · >= 3.1 and <= 3.1.11
Fixed in: newer than 3.1.11
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 3.1.11 (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 mono UPGRADE
Affected: >= 6.12.0 and < 6.12.0.122
Fixed in: 6.12.0.122
Safe to downgrade to: a release before 6.12.0
1. Check installed version
apt-cache policy mono || rpm -q mono || mono --version
2. UPGRADE to 6.12.0.122 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade mono
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade mono
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 6.12.0 (Debian / Ubuntu)
apt-cache madison mono sudo apt install mono=<VERSION_BEFORE_6.12.0> sudo apt-mark hold mono
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list mono sudo dnf downgrade mono-<VERSION_BEFORE_6.12.0> sudo dnf versionlock add mono
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 MITIGATE
Affected: all versions
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy visual-studio-2019 || rpm -q visual-studio-2019 || visual-studio-2019 --version
No fixed or unaffected release known
Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.
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-2021-24112?

.net: upgrade to newer than 5.0.2; .net core: upgrade to newer than 3.1.11; mono: upgrade to 6.12.0.122. Exact commands for each OS are on this page.

Is CVE-2021-24112 being exploited?

CVE-2021-24112 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-2021-24112 affect?

CVE-2021-24112 affects .net, .net core, mono. Severity is high (CVSS 8.1). .NET Core Remote Code Execution Vulnerability

How urgent is CVE-2021-24112?

Priority 61/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

.NET vulnerabilities · Visual Studio vulnerabilities

Related CVEs

References

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