CVE-2024-21413
Microsoft Office 2016
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
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, ranked in the top 0.1% 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
- 🇪🇺 ENISA EUVD: EUVD-2024-19122
Vulnerability Data
Microsoft Outlook Remote Code Execution Vulnerability
- CWE(s)
- KEV Date Added
- 06 February 2025
Related Threats
CVEs Like This One
Affected Assets
Mitigating Controls
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 (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.
A.8.25 mandates security requirements, secure coding guidelines, checkpoints, testing (incl. code scans) and developer training in the SDLC, which reaches a slice of input validation defects but leaves the majority (incomplete enforcement, second-order inputs, parser differentials, post-validation canonicalization) unaddressed as in the SA-3 and A.8.28 anchors.
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.
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.
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.
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.
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.
- No fine-grained STIG row for CWE-20, a class-level weakness, and none of its children carries one either.