CVE-2026-26171: Uncontrolled resource consumption in .NET allows an unauthorized attacker to deny service over a network.

Q: How do I fix CVE-2026-26171?

.net: upgrade to 8.0.26, 9.0.15, 10.0.6; powershell: upgrade to 7.5.6, 7.6.1. Exact commands for each OS are on this page.

Q: Is CVE-2026-26171 being exploited?

CVE-2026-26171 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-26171 affect?

CVE-2026-26171 affects .net, powershell. Severity is high (CVSS 7.5). Uncontrolled resource consumption in .NET allows an unauthorized attacker to deny service over a network.

Q: How urgent is CVE-2026-26171?

Priority 56/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

This month

HIGH 7.5REMOTEWATCHLISTUPGRADEUPGRADE

CVE-2026-26171 is a high-severity flaw (CVSS 7.5) affecting .net, powershell. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Uncontrolled resource consumption in .NET allows an unauthorized attacker to deny service over a network.

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 score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.8% (top 22%)
CISA exploited list	No
Weakness	CWE-400, CWE-611, CWE-776
Published	2026-04-14
Last modified	2026-10-26

Publisher (CNA): Microsoft Corporation · Vendor: microsoft

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-14 18:16 UTCPublished CVE record published
2026-10-26 22:10 UTCUpdated Record last modified

microsoft .net UPGRADE

Affected: >= 10.0.0 and < 10.0.6 · >= 8.0.0 and < 8.0.26 · >= 9.0.0 and < 9.0.15

Fixed in: 8.0.26, 9.0.15, 10.0.6

Safe to downgrade to: a release before 8.0.0

1. Check installed version

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

2. UPGRADE to 8.0.26 (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 8.0.0 (Debian / Ubuntu)

apt-cache madison .net sudo apt install .net=<VERSION_BEFORE_8.0.0> 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_8.0.0> 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 powershell UPGRADE

Affected: >= 7.5 and < 7.5.6 · >= 7.6 and < 7.6.1

Fixed in: 7.5.6, 7.6.1

Safe to downgrade to: a release before 7.5

1. Check installed version

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

2. UPGRADE to 7.5.6 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade powershell

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade powershell

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 7.5 (Debian / Ubuntu)

apt-cache madison powershell sudo apt install powershell=<VERSION_BEFORE_7.5> sudo apt-mark hold powershell

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

dnf --showduplicates list powershell sudo dnf downgrade powershell-<VERSION_BEFORE_7.5> 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.

Exact fixes by distribution

NuGet (.NET) · System.Security.Cryptography.Xml · FIXED · 10.0.6 · vulnerable: >= 10.0.0, <= 10.0.5 · source

dotnet add package System.Security.Cryptography.Xml --version 10.0.6

Fedora ELN · rust-snpguest · FIXED · 0.11.0-1.eln159 · FEDORA-2026-baa01ba6c8 · source

sudo dnf upgrade --advisory=FEDORA-2026-baa01ba6c8

Fedora 46 · rust-sev · FIXED · 8.0.0-1.fc46 · FEDORA-2026-df06b5fb0c · source

sudo dnf upgrade --advisory=FEDORA-2026-df06b5fb0c

RHEL 10 · dotnet10.0 · FIXED · dotnet10.0-10.0.106-1.el10_1

sudo dnf upgrade --advisory=RHSA-2026:8467 rpm -q dotnet10.0

RHEL 10 · dotnet8.0 · FIXED · dotnet8.0-8.0.126-1.el10_1

sudo dnf upgrade --advisory=RHSA-2026:8470 rpm -q dotnet8.0

RHEL 10 · dotnet9.0 · FIXED · dotnet9.0-9.0.116-1.el10_1

sudo dnf upgrade --advisory=RHSA-2026:8472 rpm -q dotnet9.0

RHEL 10.0 Extended Update Support · dotnet9.0 · FIXED · dotnet9.0-9.0.116-1.el10_0

sudo dnf upgrade --advisory=RHSA-2026:13280 rpm -q dotnet9.0

RHEL 10.0 Extended Update Support · dotnet8.0 · FIXED · dotnet8.0-8.0.126-1.el10_0

sudo dnf upgrade --advisory=RHSA-2026:13281 rpm -q dotnet8.0

Alpine 3.20 · dotnet8-runtime · FIXED · dotnet8-runtime-8.0.26-r0

apk add --upgrade dotnet8-runtime apk info -v dotnet8-runtime

Alpine 3.21 · dotnet8-runtime · FIXED · dotnet8-runtime-8.0.26-r0

apk add --upgrade dotnet8-runtime apk info -v dotnet8-runtime

Alpine 3.21 · dotnet9-runtime · FIXED · dotnet9-runtime-9.0.15-r0

apk add --upgrade dotnet9-runtime apk info -v dotnet9-runtime

Alpine 3.22 · dotnet8-runtime · FIXED · dotnet8-runtime-8.0.26-r0

apk add --upgrade dotnet8-runtime apk info -v dotnet8-runtime

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2026-1629 · source

sudo dnf update --advisory=ALAS2023-2026-1629

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-2026-26171?

.net: upgrade to 8.0.26, 9.0.15, 10.0.6; powershell: upgrade to 7.5.6, 7.6.1. Exact commands for each OS are on this page.

Is CVE-2026-26171 being exploited?

CVE-2026-26171 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-2026-26171 affect?

CVE-2026-26171 affects .net, powershell. Severity is high (CVSS 7.5). Uncontrolled resource consumption in .NET allows an unauthorized attacker to deny service over a network.

How urgent is CVE-2026-26171?

Priority 56/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

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References

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