How severe is CVE-2024-21413?

CVE-2024-21413 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2024-21413?

Affected package information for CVE-2024-21413 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2024-21413?

No fixed version has been published for CVE-2024-21413 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2024-21413 actively exploited in the wild?

Yes. There are 19 known exploit references for CVE-2024-21413, including 10 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2024-21413?

CVE-2024-21413 has an EPSS (Exploit Prediction Scoring System) score of 93.0%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2024-21413 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2024-21413 (Microsoft Outlook Improper Input Validation Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2025-02-06. CISA required all US federal civilian agencies to remediate this vulnerability by 2025-02-27. The required action was: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2024-21413?

CVE-2024-21413 is classified as Improper Input Validation (CWE-20). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Which products and versions are affected by CVE-2024-21413?

CVE-2024-21413 affects microsoft 365 apps; microsoft office 2016; microsoft office 2019; microsoft office long term servicing channel (1 version, e.g. 2021). Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2024-21413 published, and has it been updated?

CVE-2024-21413 was published on February 13, 2024 and was last updated on October 28, 2025. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2025-02-06 — agencies required to remediate by 2025-02-27

CVE-2024-21413

CRITICAL

Microsoft Outlook Remote Code Execution Vulnerability

Published

Feb 13, 2024

Updated

Oct 28, 2025

Affected

0 pkgs

Patched

None yet

Exploits

19 known

EPSS Exploitation Probability

via FIRST.org ↗

93.0%probability of exploitation in next 30 days

Very High Risk100th percentile-0.03%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

Microsoft Outlook Remote Code Execution Vulnerability

Affected Products

4 products · 6 configurations

Application

365 appsmicrosoft

all

Application

office 2016microsoft

all

Application

office 2019microsoft

all

Application

office long term servicing channelmicrosoft

1 version

2021

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Microsoft Outlook Remote Code Execution Vulnerability

portal.msrc.microsoft.comMSFeb 2024

Microsoft Outlook Remote Code Execution Vulnerability

github.comGithubFeb 2024

Microsoft Outlook Remote Code Execution Vulnerability

github.comGithubFeb 2024

Microsoft Outlook Remote Code Execution Vulnerability

github.comGithubFeb 2024

Microsoft Outlook Remote Code Execution Vulnerability

github.comGithubFeb 2024

Microsoft Outlook Remote Code Execution Vulnerability

github.comGithubFeb 2024

Microsoft Outlook Remote Code Execution Vulnerability

github.comGithubFeb 2024

Microsoft Outlook Remote Code Execution Vulnerability

github.comGithubFeb 2024

Microsoft Outlook Remote Code Execution Vulnerability

Old revision of MS report mistakenly flagged CVE-2024-21413 as exploited in the wild. It was fixed in version 1.2 (the current version). InTheWild still shows it as actively expoited. https://msrc.microsoft.com/update-guide/en-US/advisory/CVE-2024-21413APIFeb 2024

Microsoft Outlook Remote Code Execution Vulnerability

github.comGithubAug 2024

Frequently Asked Questions

Microsoft Outlook Remote Code Execution Vulnerability

O3 Security · Impact-Aware SCA

Is CVE-2024-21413 in your stack?

O3 detects CVE-2024-21413 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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