PatchTheCVECVE-2026-55054: Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a ne
43
This month
MEDIUM 6.5WATCHLISTMITIGATEDOWNGRADEDOWNGRADE
CVE-2026-55054 is a medium-severity flaw (CVSS 6.5) affecting 365 apps, excel, office. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.
Why this priority
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 6.5 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | Required |
| EPSS exploit chance | 0.9% (top 40%) |
| CISA exploited list | No |
| Weakness | CWE-125 |
| Published | 2026-07-14 |
| Last modified | 2026-07-15 |
Publisher (CNA): Microsoft Corporation · Vendor: microsoft
Last updated 2026-07-15 · 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 excel DOWNGRADE
Affected: 2016
Fixed in: no fixed release known
Safe to downgrade to: a release before 2016
1. Check installed version
apt-cache policy excel || rpm -q excel || excel --version
2. No fixed release: DOWNGRADE to a release before 2016 (Debian / Ubuntu)
apt-cache madison excel
sudo apt install excel=<VERSION_BEFORE_2016>
sudo apt-mark hold excel
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list excel
sudo dnf downgrade excel-<VERSION_BEFORE_2016>
sudo dnf versionlock add excel
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 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 2021 UPGRADE
Affected: < 16.111.26071215
Fixed in: 16.111.26071215
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy office-2021 || rpm -q office-2021 || office-2021 --version
2. UPGRADE to 16.111.26071215 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade office-2021
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade office-2021
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
microsoft office 2021 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 office-2021 || rpm -q office-2021 || office-2021 --version
No fixed or unaffected release known
Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.
microsoft office 2024 UPGRADE
Affected: < 16.111.26071215
Fixed in: 16.111.26071215
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy office-2024 || rpm -q office-2024 || office-2024 --version
2. UPGRADE to 16.111.26071215 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade office-2024
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade office-2024
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
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-2026-55054?
365 apps: mitigate or apply the listed mitigation; excel: downgrade or apply the listed mitigation; office: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2026-55054 being exploited?
CVE-2026-55054 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-2026-55054 affect?
CVE-2026-55054 affects 365 apps, excel, office. Severity is medium (CVSS 6.5). Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.
How urgent is CVE-2026-55054?
Priority 43/100. On your watchlist
Software pages
Microsoft Office vulnerabilities
Related CVEs
- CVE-2026-23657 HIGH 7.8 MITIGATE DOWNGRADE Use after free in Microsoft Office Word allows an unauthorized attacker to execute code locally.
- CVE-2026-32190 HIGH 8.4 MITIGATE DOWNGRADE Use after free in Microsoft Office allows an unauthorized attacker to execute code locally.
- CVE-2026-32189 HIGH 7.8 MITIGATE DOWNGRADE Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
- CVE-2026-32188 HIGH 7.1 MITIGATE DOWNGRADE Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.
- CVE-2026-32200 HIGH 7.8 MITIGATE DOWNGRADE Use after free in Microsoft Office PowerPoint allows an unauthorized attacker to execute code locally.