PatchTheCVECVE-2026-40364: Access of resource using incompatible type ('type confusion') in Microsoft Office Word allows an unauthorized
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This month
HIGH 8.4WATCHLISTMITIGATEDOWNGRADEDOWNGRADE
CVE-2026-40364 is a high-severity flaw (CVSS 8.4) affecting 365 apps, office, office long term servicing channel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Access of resource using incompatible type ('type confusion') in Microsoft Office Word allows an unauthorized attacker to execute code locally.
Why this priority
- High severity
- EPSS top 9%: very likely to be exploited
- On your watchlist
A fixed release or distro patch exists.
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
- Published CVE record published
- Updated Record last modified
microsoft 365 apps 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 365-apps || rpm -q 365-apps || 365-apps --version
No fixed or unaffected release known
Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.
microsoft office DOWNGRADE
Affected: 2019
Fixed in: no fixed release known
Safe to downgrade to: a release before 2019
1. Check installed version
apt-cache policy office || rpm -q office || office --version
2. No fixed release: DOWNGRADE to a release before 2019 (Debian / Ubuntu)
apt-cache madison office
sudo apt install office=<VERSION_BEFORE_2019>
sudo apt-mark hold office
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list office
sudo dnf downgrade office-<VERSION_BEFORE_2019>
sudo dnf versionlock add office
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 office long term servicing channel DOWNGRADE
Affected: 2021 · 2024
Fixed in: no fixed release known
Safe to downgrade to: a release before 2021
1. Check installed version
apt-cache policy office-long-term-servicing-channel || rpm -q office-long-term-servicing-channel || office-long-term-servicing-channel --version
2. No fixed release: DOWNGRADE to a release before 2021 (Debian / Ubuntu)
apt-cache madison office-long-term-servicing-channel
sudo apt install office-long-term-servicing-channel=<VERSION_BEFORE_2021>
sudo apt-mark hold office-long-term-servicing-channel
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list office-long-term-servicing-channel
sudo dnf downgrade office-long-term-servicing-channel-<VERSION_BEFORE_2021>
sudo dnf versionlock add office-long-term-servicing-channel
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 office long term servicing channel DOWNGRADE
Affected: 2021 · 2024
Fixed in: no fixed release known
Safe to downgrade to: a release before 2021
1. Check installed version
apt-cache policy office-long-term-servicing-channel || rpm -q office-long-term-servicing-channel || office-long-term-servicing-channel --version
2. No fixed release: DOWNGRADE to a release before 2021 (Debian / Ubuntu)
apt-cache madison office-long-term-servicing-channel
sudo apt install office-long-term-servicing-channel=<VERSION_BEFORE_2021>
sudo apt-mark hold office-long-term-servicing-channel
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list office-long-term-servicing-channel
sudo dnf downgrade office-long-term-servicing-channel-<VERSION_BEFORE_2021>
sudo dnf versionlock add office-long-term-servicing-channel
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 word DOWNGRADE
Affected: 2016
Fixed in: no fixed release known
Safe to downgrade to: a release before 2016
1. Check installed version
apt-cache policy word || rpm -q word || word --version
2. No fixed release: DOWNGRADE to a release before 2016 (Debian / Ubuntu)
apt-cache madison word
sudo apt install word=<VERSION_BEFORE_2016>
sudo apt-mark hold word
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list word
sudo dnf downgrade word-<VERSION_BEFORE_2016>
sudo dnf versionlock add word
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
A distro patch exists: prefer upgrading over downgrading.
Fedora ELN · xfsdump · FIXED · 3.3.0-3.eln159 · FEDORA-2026-6e9bb3f901 · source
sudo dnf upgrade --advisory=FEDORA-2026-6e9bb3f901
Fedora 46 · fio · FIXED · 3.43-2.fc46 · FEDORA-2026-b36219886b · source
sudo dnf upgrade --advisory=FEDORA-2026-b36219886b
Install KB5002858 via Windows Update, then verify:
Get-HotFix -Id KB5002858
Install KB5002858 via Windows Update, then verify:
Get-HotFix -Id KB5002858
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.
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-2026-40364?
365 apps: mitigate or apply the listed mitigation; office: downgrade or apply the listed mitigation; office long term servicing channel: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2026-40364 being exploited?
CVE-2026-40364 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-2026-40364 affect?
CVE-2026-40364 affects 365 apps, office, office long term servicing channel. Severity is high (CVSS 8.4). Access of resource using incompatible type ('type confusion') in Microsoft Office Word allows an unauthorized attacker to execute code locally.
How urgent is CVE-2026-40364?
Priority 57/100. High severity; EPSS top 9%: very likely to be exploited; On your watchlist
Software pages
Microsoft Office vulnerabilities
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