⚠ Reference material — not professional advice. Test in staging, back up first, verify against your specific version. Use your own judgment for your environment.
● High · CVSS 7.7

How to Fix CVE-2026-42832: Access Control Bypass in Microsoft Excel for Android

Other vulnerabilities in the same area that are worth patching alongside this one:

*By Sai Kiran Pandrala*

⚡ At a glance
SeverityCVSS 7.7 - High
Actively exploited?Not currently listed in CISA KEV
Affected16.0.0.0 < 16.0.19822.20190, 16.0.1 < 16.109.26051019, 16.0.0 < 16.109.26051019, 16.0.0.0 < 16.0.19822.20190
Fixed inSee vendor advisory
Type (CWE)CWE-284: Improper Access Control

What is CVE-2026-42832?

CVE-2026-42832 is an access control bypass flaw in Microsoft Excel for Android. Authenticated or in some cases unauthenticated requests reach endpoints they should not be allowed to call, exposing administrative functionality or sensitive data. Vendor description: Improper access control in Microsoft Office allows an unauthorized attacker to perform spoofing locally.

Why this CVE matters

Access control flaws let an attacker reach endpoints the developers assumed would be reserved for administrators. The impact depends on what those endpoints expose, but for management products the answer is usually configuration changes, log access, or credential reads.

For deployments of Microsoft Excel for Android that have been exposed to the public internet during the disclosure window, the operating assumption should be that scanning has already happened. Even where exploitation has not been publicly observed, scanning for the vulnerable fingerprint is cheap and routine. Patching closes the door; log review and credential rotation close out the rest of the response.

Am I affected?

You are affected if your installation matches any of these version ranges:

Check your installed version against the list above. If you cannot determine the version, treat the system as affected and follow the upgrade path below.

On Windows, check the product's installed version via Settings - Apps - Installed apps, or run Get-Package from PowerShell to enumerate installed versions.

How to fix CVE-2026-42832

  1. Read the vendor advisory in full: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42832
  2. Upgrade Microsoft Excel for Android to the patched build listed in the vendor advisory.
  3. Back up the configuration (and database, where applicable) before upgrading.
  4. Apply the patch in a maintenance window. For HA pairs, upgrade the standby node first, fail over, then upgrade the former primary.
  5. Restart the affected service so the patched binary loads, then verify the new version (see verification section).

# Confirm managed Android devices have the patch (Intune via Microsoft Graph).
Connect-MgGraph -Scopes Device.Read.All
Get-MgDeviceManagementManagedDevice -Filter "operatingSystem eq 'Android'" |
  Select-Object DeviceName, OSVersion, AndroidSecurityPatchLevel

Apply the Android security bulletin update


# CVE-2026-42832 affects Android 16.0.0.0 < 16.0.19822.20190. Fixed in 16.0.19822.20190.
# Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42832

# 1. Confirm the device's current security patch level.
adb shell getprop ro.build.version.security_patch

# 2. The patch level must be on or after the date listed in the advisory.
#    If older, install the OTA from Settings -> System -> System update,
#    or sideload the factory image:
adb reboot bootloader
fastboot flash bootloader bootloader-<device>-<build>.img
fastboot reboot bootloader
fastboot -w update image-<device>-<build>.zip


# Confirm managed Android devices have the patch (Intune via Microsoft Graph).
Connect-MgGraph -Scopes Device.Read.All
Get-MgDeviceManagementManagedDevice -Filter "operatingSystem eq 'Android'" |
  Select-Object DeviceName, OSVersion, AndroidSecurityPatchLevel

Verify the fix landed


# CVE-2026-42832 verification checklist.

# 1. Confirm the running version matches 16.0.19822.20190 (replace the version probe with
#    the platform-specific command shown above).

# 2. Re-scan the host with your vulnerability scanner (Nessus, Qualys, Tenable,
#    OpenVAS, Wazuh). The scanner must no longer flag CVE-2026-42832.

# 3. Inspect recent service and kernel logs for crash-loops or rollback events.
journalctl -u <service-name> --since "10 minutes ago"
dmesg --since "10 minutes ago"

# 4. Cross-check the running build against the vendor advisory:
#    https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42832

If you cannot patch immediately

No official workaround exists beyond restricting network exposure to the affected component. Apply the vendor patch as the primary remediation.

How to verify the fix worked

If your installation was internet-reachable during the disclosure window, treat log review as part of the remediation rather than an optional follow-up. Look for log entries that do not match your normal request patterns, especially repeated requests to the same uncommon endpoint, and any administrative changes you cannot tie back to a known operator.

Frequently asked questions

Is CVE-2026-42832 being exploited in the wild?

Public exploitation has not been confirmed by CISA at the time of writing. Treat the patch as time-sensitive anyway; reports often lag actual abuse.

Will a WAF or IDS rule fully mitigate CVE-2026-42832?

No. Network-layer filters can reduce noise and slow opportunistic scanners, but they will not stop a determined attacker. The vendor patch is the only durable fix.

How long should I plan for the upgrade?

Typical vendor-documented upgrade windows for Microsoft Excel for Android run from a few minutes to under an hour depending on cluster size. Test in a staging environment first and follow the vendor's documented HA upgrade order.

References

*This guide was assembled from the official vendor advisory, the NVD record, and the CISA KEV catalog entry on 2026-05-25. Always confirm against the vendor advisory before applying changes in production.*