Cyber Resilience

CVE-2024-21413

Microsoft Office 2016

CISA KEVActive ExploitationEUVD ExploitedPublic PoC
Published
13 February 2024
Modified
10 August 2026
KEV Added
06 February 2025
Patch / advisory
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.95 99.8th percentile
Risk Priority 97 floored blend · peak EPSS

Summary

CVE-2024-21413 is a critical-severity Improper Input Validation (CWE-20) vulnerability in Microsoft Office 2016. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 0.2% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

Microsoft Outlook contains a remote code execution vulnerability, CVE-2024-21413, that arises from improper input validation (CWE-20) in the handling of MonikerLink objects. The flaw affects the Microsoft Outlook email client and received a CVSS 3.1 score of 9.8, reflecting network-accessible attack vectors that require neither authentication nor user interaction.

An unauthenticated remote attacker can exploit the issue by delivering a crafted message or link that triggers code execution, resulting in complete loss of confidentiality, integrity, and availability on the affected system.

Microsoft has published official guidance and patches through its security update guide at msrc.microsoft.com. Additional technical analysis from Check Point Research describes the underlying moniker-link mechanism, while Vicarius has released corresponding detection and mitigation scripts.

The EPSS score currently stands at 0.9296 with a recorded peak of 0.9350.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

Microsoft Outlook Remote Code Execution Vulnerability

CWE(s)
KEV Date Added
06 February 2025

Related Threats

MITRE ATT&CK Enterprise Techniques

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
T1036.001 Invalid Code Signature Stealth
Adversaries may attempt to mimic features of valid code signatures to increase the chance of deceiving a user, analyst, or tool.
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-38189Same product: Microsoft 365 Appsboth on KEV
CVE-2023-36761Same product: Microsoft 365 Appsboth on KEV
CVE-2020-1350Same vendor: Microsoftboth on KEV
CVE-2025-32706Same vendor: Microsoftboth on KEV
CVE-2012-0151Same vendor: Microsoftboth on KEV
CVE-2018-8414Same vendor: Microsoftboth on KEV
CVE-2020-1040Same vendor: Microsoftboth on KEV
CVE-2026-32201Same vendor: Microsoftboth on KEV
CVE-2019-0604Same vendor: Microsoftboth on KEV
CVE-2024-30040Same vendor: Microsoftboth on KEV

Affected Assets

microsoft
365 apps
all versions
microsoft
office 2016
all versions
microsoft
office 2019
all versions
microsoft
office long term servicing channel
2021

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)
  • 6 hardening rules · 3 OS baselines
Validate
Prove the fix (OWASP ASVS)

Mitigating Controls (NIST 800-53 r5) AI

Developer testing and evaluation can discover missing input validation through analysis or test cases.

SI-10 directly requires validity checks on information inputs, structurally preventing improper or missing validation.

Requiring documented development standards and tools can embed input-validation practices into the engineering process.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require and enforce input validation during development.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

finds

Testing against a defined set of requirements and using code review plus vulnerability scanning forces validation of inputs and handling of unanticipated conditions, reducing the chance that malformed data will be accepted.

prevents

Secure-coding guidelines and mandatory security testing (including code scans) compel developers to validate and sanitize inputs at design and implementation time, lowering the incidence of malformed or malicious data reaching downstream components.

prevents

Mandating input controls that include integrity checks and input validation ensures that untrusted data is examined before use, blocking the root cause of many injection and malformed-data weaknesses.

prevents

Security-by-design principles explicitly call for data validation and sanitization at every layer, reducing the chance that malformed or malicious input will be processed without scrutiny.

prevents

Requiring language-specific secure coding standards, peer review, SAST and documented mitigation of common programming errors forces validation of all inputs before they are trusted.

none

Regular automated validation of system software and data content, combined with scanning of all inbound files, enforces input validation at the boundary before untrusted content is processed.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

RHEL 8 (1 rule)
  • V-230265 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-20

References