---
id: "CVE-2024-21413"
kind: "vulnerability"
aliases: ["CVE-2024-21413"]
title: "Microsoft Outlook Remote Code Execution Vulnerability"
severity: "critical"
cvss: 9.8
epss: null
exploited: true
status: "open"
category: "other"
products: [{"name": "Microsoft Office Outlook", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft 365 apps", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft office 2016", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft office 2019", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "microsoft office long term servicing channel", "fixed": [], "affected": "= 2021", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "microsoft-office", "other", "outlook", "windows"]
not_affected_if: ["unknown"]
published_at: "2024-02-13T18:16:00+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-23T22:29:05+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2024-21413", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-21413", "first_seen_at": "2026-10-23T22:29:05+00:00"}]
---

# Microsoft Outlook Remote Code Execution Vulnerability

Microsoft Outlook has an improper input validation flaw in how it handles links, which lets a crafted message bypass Office Protected View and open content in editing mode. The sources say the bug allows remote code execution and that it is being exploited in the wild.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Microsoft Office Outlook affected ? fixed ?
- vendor:microsoft 365 apps affected ? fixed ?
- vendor:microsoft office 2016 affected ? fixed ?
- vendor:microsoft office 2019 affected ? fixed ?
- vendor:microsoft office long term servicing channel affected = 2021 fixed ?

## Fix

Apply mitigations per vendor instructions, or discontinue use of the product if mitigations are unavailable (per CISA required action).

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2024-21413
- 2026-10-23T22:29:05+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2024-21413

## From the sources

Microsoft Outlook contains an improper input validation vulnerability that allows for remote code execution. Successful exploitation of this vulnerability would allow an attacker to bypass the Office Protected View and open in editing mode rather than protected mode.

CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_