PatchTheCVECVE-2026-54123: Exposure of sensitive information to an unauthorized actor in Microsoft Defender for Endpoint allows an author
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Routine
MEDIUM 5.5WATCHLISTUPGRADE
CVE-2026-54123 is a medium-severity flaw (CVSS 5.5) affecting defender for endpoint. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Exposure of sensitive information to an unauthorized actor in Microsoft Defender for Endpoint allows an authorized attacker to disclose information locally.
Why this priority
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 5.5 (Medium) |
| Attack vector | Local |
| Attack complexity | Low |
| Privileges needed | Low |
| User interaction | None |
| EPSS exploit chance | 0.5% (top 60%) |
| CISA exploited list | No |
| Weakness | CWE-200 |
| Published | 2026-08-11 |
| Last modified | 2026-10-23 |
Publisher (CNA): Microsoft Corporation · Vendor: microsoft
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
microsoft defender for endpoint UPGRADE
Affected: >= 101.0.0 and < 101.26042.0020
Fixed in: 101.26042.0020
Safe to downgrade to: a release before 101.0.0
1. Check installed version
apt-cache policy defender-for-endpoint || rpm -q defender-for-endpoint || defender-for-endpoint --version
2. UPGRADE to 101.26042.0020 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade defender-for-endpoint
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade defender-for-endpoint
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 101.0.0 (Debian / Ubuntu)
apt-cache madison defender-for-endpoint
sudo apt install defender-for-endpoint=<VERSION_BEFORE_101.0.0>
sudo apt-mark hold defender-for-endpoint
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list defender-for-endpoint
sudo dnf downgrade defender-for-endpoint-<VERSION_BEFORE_101.0.0>
sudo dnf versionlock add defender-for-endpoint
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
Fedora 46 · clementine · FIXED · 1.4.2-1.fc46 · FEDORA-2026-3e748ef4d3 · source
sudo dnf upgrade --advisory=FEDORA-2026-3e748ef4d3
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.