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OutlookApplication · Microsoft

CVE-2026-42893

HIGH · 7.5 CVSS v3.1 Published 2026-05-12
Fix available
A fix is available. Upgrade to 5.2617.1 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an unauthorized attacker to perform tampering over a network.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

This is a command injection vulnerability in M365 Copilot where improper neutralization of special elements allows an attacker to inject malicious commands. The vulnerability is remotely exploitable over a network and enables tampering, likely through manipulated inputs processed by Copilot's command execution layer.

MitigationOrganizations should monitor for Microsoft security updates for M365 Copilot and apply patches promptly. Input validation and sanitization enhancements on the service side (Microsoft) are required to prevent special character injection into executed commands.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
OutlookApplication
Affected:< 5.2617.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify Microsoft Outlook is installed
    Check for Microsoft Outlook installation via Add/Remove Programs on Windows, or run 'ls /Applications | grep -i Outlook' on macOS, or check package manager on Linux
    Affected if Microsoft Outlook is not installed on the system
  2. Find installed Outlook version
    In Windows: Open Outlook, go to File > Office Account > About Outlook. Alternatively, run 'Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | Where-Object {$_.DisplayName -like "*Outlook*"} | Select-Object DisplayVersion' in PowerShell. On macOS: Right-click Outlook in Applications > Get Info > Version
    Affected if Unable to determine the installed version
  3. Confirm M365 Copilot integration is enabled
    In Outlook desktop: Go to File > Options > Copilot (or search for Copilot settings in the ribbon). Check if Copilot features are configured or available in the account. On Outlook web: Check for Copilot pane or settings
    Affected if M365 Copilot is not enabled or not available for the account
  4. Compare version against affected range
    Take the discovered version number and compare it numerically to 5.2617.1 - any version below 5.2617.1 is affected
    Affected if Installed version is less than 5.2617.1 (for example, 5.2616.0, 5.2600.0, etc.)

A user is affected if Microsoft Outlook with M365 Copilot is installed and the Outlook version is below 5.2617.1.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.2617.1 or later
Fixed in 5.2617.1
Interim mitigation

Organizations should monitor for Microsoft security updates for M365 Copilot and apply patches promptly. Input validation and sanitization enhancements on the service side (Microsoft) are required to prevent special character injection into executed commands.

Recommended fix High confidence

Microsoft Outlook version 5.2617.1 (M365 Copilot component)

  1. Open Microsoft Outlook and navigate to File > Office Account to check the current version number
  2. If automatic updates are enabled, the application should auto-update to version 5.2617.1 or later; restart Outlook to trigger the update if needed
  3. For managed enterprise environments, use Microsoft Intune, Configuration Manager (SCCM), or Group Policy to deploy the latest Microsoft 365 / Office update containing the Outlook fix
  4. Alternatively, open any Office app, go to File > Account > Update Options > Update Now to manually trigger an immediate update
  5. After updating, verify the fix by checking File > Office Account to confirm the version displays 5.2617.1 or higher
Caveat Minimal risk; standard Microsoft 365 monthly updates typically include backward-compatible fixes; enterprise should test in pilot group before broad deployment

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Outlook Scoped from the published advisory
  • Consultation6.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,840
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,144.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-42893 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data