Microsoft · Office Outlook

CVE-2024-21413

Microsoft Outlook Improper Input Validation Vulnerability

Evidence

Source & freshness

Full source status →

CISA KEV catalog Core KEV record

CVE, vendor/product, CISA dates, ransomware status, description, required action, and notes.

Catalog 2026.07.24 · Retrieved 2026-07-25 20:49 UTC Open official CISA feed ↗

MITRE CWE catalog CWE context

CWE names and plain-language weakness descriptions. CISA supplies the CWE assignment itself.

Retrieved 2026-07-25 20:59 UTC Open official MITRE CWE catalog ↗

National Vulnerability Database NVD technical context

CVSS metrics, NVD timeline, and related NVD record data are stored locally.

Retrieved Jul 25, 2026, 08:49 PM UTC Open NVD record ↗

CISA KEV record

CISA date added: 2025-02-06
CISA due date: 2025-02-27
Known ransomware use: Unknown

NVD risk context

9.8 CRITICAL

CVSS is a technical severity score. CISA’s KEV status remains the evidence that this vulnerability is known to be exploited.

View NVD record ↗

Attack vector

Network

The vulnerable service can be reached remotely over a network.

Attack complexity

Low

Exploitation does not require unusual conditions beyond normal attacker control.

Privileges required

None

The attacker does not need an existing account or privileges.

User interaction

None

No action by another user is required.

Description

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.

Required action

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

NVD reference index

Vendor and remediation references

NVD has tagged these sources as vendor advisories, patches, mitigations, or release notes.

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21413 ↗
PatchVendor Advisory NVD reference source: secure@microsoft.com · Also linked in CISA notes
https://www.vicarius.io/vsociety/posts/cve-2024-21413-critical-monikerlink-vulnerability-affecting-microsoft-outlook-mitigation-script ↗
Mitigation NVD reference source: af854a3a-2127-422b-91ae-364da2661108

Other NVD references (3)

https://research.checkpoint.com/2024/the-risks-of-the-monikerlink-bug-in-microsoft-outlook-and-the-big-picture/ ↗
Technical Description NVD reference source: af854a3a-2127-422b-91ae-364da2661108
https://www.vicarius.io/vsociety/posts/cve-2024-21413-critical-monikerlink-vulnerability-affecting-microsoft-outlook-detection-script ↗
Exploit NVD reference source: af854a3a-2127-422b-91ae-364da2661108
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-21413 ↗
US Government Resource NVD reference source: 134c704f-9b21-4f2e-91b3-4a467353bcc0

MITRE CWE context

CWE classification

CWE-20 Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

View official MITRE CWE details ↗

NVD record timing

NVD record timeline

These dates describe NVD’s record, not CISA’s KEV addition or remediation due date.

NVD published: Feb 13, 2024, 06:16 PM UTC
NVD last updated: Jun 17, 2026, 07:09 AM UTC

Advanced: view the technical CVSS vector

This standardized code is intended for security tools and technical analysts. The plain-language risk summary above explains its main points.

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

View NVD record ↗

CISA notes

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21413 ; https://nvd.nist.gov/vuln/detail/CVE-2024-21413