CVE-2026-35433: Improper input validation in .NET allows an unauthorized attacker to elevate privileges locally.

This month

HIGH 7.3WATCHLISTDOWNGRADEUPGRADE

CVE-2026-35433 is a high-severity flaw (CVSS 7.3) affecting .net framework, .net. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Improper input validation in .NET allows an unauthorized attacker to elevate privileges locally.

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.3 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.8% (top 45%)
CISA exploited list	No
Weakness	CWE-20, CWE-190
Published	2026-05-12
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

2026-05-12 18:17 UTCPublished CVE record published
2026-10-26 18:10 UTCUpdated Record last modified

microsoft .net framework DOWNGRADE

Affected: 4.8 · 3.5 · 4.8.1 · 4.7.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.5

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 3.5 (Debian / Ubuntu)

apt-cache madison .net-framework sudo apt install .net-framework=<VERSION_BEFORE_3.5> 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_3.5> 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 .net UPGRADE

Affected: >= 8.0.0 and < 8.0.27 · >= 9.0.0 and < 9.0.16 · >= 10.0.0 and < 10.0.8

Fixed in: 8.0.27, 9.0.16, 10.0.8

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 8.0.27 (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.

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-2026-35433?

.net framework: downgrade or apply the listed mitigation; .net: upgrade to 8.0.27, 9.0.16, 10.0.8. Exact commands for each OS are on this page.

Is CVE-2026-35433 being exploited?

CVE-2026-35433 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-2026-35433 affect?

CVE-2026-35433 affects .net framework, .net. Severity is high (CVSS 7.3). Improper input validation in .NET allows an unauthorized attacker to elevate privileges locally.

How urgent is CVE-2026-35433?

Priority 44/100. High severity; On your watchlist

Software pages

.NET vulnerabilities

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References

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