Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 27 Feb 2025.
365 AppsApplication · Microsoft

CVE-2024-21413

CRITICAL · 9.8 CVSS v3.1 Published 2024-02-13
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
In the wild High EPSS Public exploit Remotely reachable No privileges Zero-click Patch available

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
Microsoft Outlook Remote Code Execution Vulnerability

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

A critical Remote Code Execution vulnerability in Microsoft Outlook that allows attackers to execute arbitrary code via specially crafted emails or hyperlinks. The CVSS 9.8 score indicates severe potential for complete system compromise with no user interaction required beyond receiving or viewing the malicious email.

MitigationApply Microsoft security updates for Outlook immediately. As an interim measure, disable automatic hyperlink preview or external content loading in Outlook settings.

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
365 AppsApplication
Affected:all versions
Office 2016Application
Affected:all versions
Office 2019Application
Affected:all versions
Office Long Term Servicing ChannelApplication
Affected:= 2021

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
High
Integrity
High
Availability
High

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

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. Identify installed Outlook version
    Open Outlook, go to File > Account Settings > About Outlook, or run 'winword.exe /?' from command line to check Office version
    Affected if The version matches Microsoft 365 Apps, Office 2016, Office 2019, or Office Long Term Servicing Channel 2021 (all versions of these products are listed as affected)
  2. Confirm Outlook is the email client
    Check default mail application in Windows Settings > Apps > Default apps, or verify Outlook is set as default handler for mailto: links
    Affected if Outlook is configured as the default email client, making it reachable via specially crafted mailto: links or malicious emails
  3. Check for security update installation
    In Outlook, go to File > Office Account > Update Options > View Update History, or check Windows Update history for recent Microsoft Outlook security updates
    Affected if No Outlook security updates from February 2024 or later have been installed (this CVE was patched in February 2024)

If Outlook is installed and no February 2024 or later security updates have been applied, the environment is likely affected by this vulnerability.

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
Patch available Apply the vendor patch
Vendor patch msrc.microsoft.com →
Interim mitigation

Apply Microsoft security updates for Outlook immediately. As an interim measure, disable automatic hyperlink preview or external content loading in Outlook settings.

Recommended fix High confidence

Microsoft security updates (February 2024) for Office/Outlook - apply all applicable security updates for your specific Office version

  1. Install Microsoft security updates for February 2024, which address CVE-2024-21413. For Outlook desktop clients, apply the appropriate security update for your Office version via Windows Update or the Microsoft Update Catalog.
  2. Ensure Microsoft Outlook is updated to a version that includes the security fix. For Office 365/Microsoft 365 Apps, updates are delivered automatically; manually check for updates via File > Account > Update Options > Update Now.
  3. For organizations using Microsoft Endpoint Manager or WSUS, deploy the February 2024 security updates to all affected endpoints.
  4. Verify the update was applied successfully by checking the installed Office version and confirming the security patch is present.
Caveat Standard Office updateapply with no special breaking changes expected; standard update deployment testing recommended

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

Fix this in 365 Apps Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2024-21413 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

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-2024-21413 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