# CVE-2024-21413: Microsoft Outlook Improper Input Validation

> Attackers can execute arbitrary code via malicious emails in Microsoft Outlook, requiring users to apply vendor patches.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C`)
- **Exploited in the wild:** Yes, since 6 Feb 2025 (CISA KEV)
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 13 Feb 2024
- **Updated:** 10 Aug 2026
- **Also known as:** GHSA-9mp4-h7q5-2rgq

## What is CVE-2024-21413?

CVE-2024-21413 is a critical code injection vulnerability in Microsoft 365 Apps, published on 13 Feb 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Microsoft Outlook Remote Code Execution Vulnerability

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2024-21413?

It affects 4 products.


Products: Microsoft 365 Apps, Microsoft Office 2016, Microsoft Office 2019, Microsoft Office Long Term Servicing Channel.

## How do I fix CVE-2024-21413?

No fix has been published for CVE-2024-21413 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 27 Feb 2025.

## Is CVE-2024-21413 being exploited?

Yes. Attackers have exploited CVE-2024-21413 in the wild since at least 6 Feb 2025.

Public exploit code:

- Microsoft-Outlook-Remote-Code-Execution-Vulnerability (github_poc): https://github.com/xaitax/CVE-2024-21413-Microsoft-Outlook-Remote-Code-Execution-Vulnerability
- CVE-2024-21413 PoC for THM Lab (github_poc): https://github.com/CMNatic/CVE-2024-21413
- Microsoft Outlook Information Disclosure Vulnerability (leak password hash) - Expect Script POC (github_poc): https://github.com/duy-31/CVE-2024-21413
- CVE-2024-21413 | Microsoft Outlook Remote Code Execution Vulnerability PoC (github_poc): https://github.com/ThemeHackers/CVE-2024-21413
- Microsoft Outlook Information Disclosure Vulnerability (leak password hash) - CVE-2024-21413 POC (github_poc): https://github.com/r00tb1t/CVE-2024-21413-POC
- Outlook exploitation (github_poc): https://github.com/mmathivanan17/CVE-2024-21413

## Other vulnerabilities in Microsoft 365 Apps

- [CVE-2023-23397](https://insights.sbomify.com/CVE-2023-23397/): Microsoft Office Outlook Privilege Escalation (critical 9.8, exploited in the wild)
- [CVE-2024-38189](https://insights.sbomify.com/CVE-2024-38189/): Microsoft Project Remote Code Execution Vulnerability (high 8.8, exploited in the wild)
- [CVE-2023-35311](https://insights.sbomify.com/CVE-2023-35311/): Microsoft Outlook Security Feature Bypass (high 8.8, exploited in the wild)
- [CVE-2026-21514](https://insights.sbomify.com/CVE-2026-21514/): Microsoft Office Word Reliance on Untrusted Inputs in a Security Decision (high 7.8, exploited in the wild)
- [CVE-2026-21509](https://insights.sbomify.com/CVE-2026-21509/): Microsoft Office Security Feature Bypass (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-21413 and fix it if it is affected.

What it is: CVE-2024-21413 is a critical code injection vulnerability in Microsoft 365 Apps, published on 13 Feb 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2024-21413 in the wild since at least 6 Feb 2025.

Affected product: Microsoft 365 Apps. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-21413/ (Markdown: https://insights.sbomify.com/CVE-2024-21413/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-21413
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-21413
- OSV: https://osv.dev/vulnerability/CVE-2024-21413

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-21413/
Summaries are generated and may contain mistakes; the official description above is the record.