CVE-2026-26143: Improper input validation in Microsoft PowerShell allows an unauthorized attacker to bypass a security feature

This month

HIGH 7.8WATCHLISTUPGRADE

CVE-2026-26143 is a high-severity flaw (CVSS 7.8) affecting powershell. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Improper input validation in Microsoft PowerShell allows an unauthorized attacker to bypass a security feature locally.

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.5% (top 55%)
CISA exploited list	No
Weakness	CWE-20
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 21:10 UTCUpdated Record last modified

microsoft powershell UPGRADE

Affected: >= 7.4 and < 7.4.14 · >= 7.5 and < 7.5.5

Fixed in: 7.4.14, 7.5.5

Safe to downgrade to: a release before 7.4

1. Check installed version

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

2. UPGRADE to 7.4.14 (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 7.4 (Debian / Ubuntu)

apt-cache madison powershell sudo apt install powershell=<VERSION_BEFORE_7.4> 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_7.4> 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-2026-26143?

powershell: upgrade to 7.4.14, 7.5.5. Exact commands for each OS are on this page.

Is CVE-2026-26143 being exploited?

CVE-2026-26143 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-2026-26143 affect?

CVE-2026-26143 affects powershell. Severity is high (CVSS 7.8). Improper input validation in Microsoft PowerShell allows an unauthorized attacker to bypass a security feature locally.

How urgent is CVE-2026-26143?

Priority 44/100. High severity; On your watchlist

Software pages

PowerShell vulnerabilities

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References

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