How severe is CVE-2024-21378?

CVE-2024-21378 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2024-21378 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 11% (96th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2024-21378?

CVE-2024-21378 primarily affects Microsoft 365 Apps. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2024-21378?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2024-21378 have an EU (EUVD) identifier?

Yes. CVE-2024-21378 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-19090.

When was CVE-2024-21378 published?

CVE-2024-21378 was published on 2024-02-13 and last updated on 2026-08-10.

CVE-2024-21378

CVE-2024-21378 is a high-severity vulnerability in Microsoft 365 Apps with a CVSS 3.x base score of 8.8. Its EPSS exploit-prediction score of 11% places it in the 96th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-94.

Key facts

Severity: High (CVSS 3.x base score 8.8)
EPSS exploit prediction: 11% (96th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2024-19090
Weakness: CWE-94
Affected product: Microsoft 365 Apps
Published: 2024-02-13
Last modified: 2026-08-10

Description

Microsoft Outlook Remote Code Execution Vulnerability

Frequently asked questions

What is CVE-2024-21378?: Microsoft Outlook Remote Code Execution Vulnerability
How severe is CVE-2024-21378?: CVE-2024-21378 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2024-21378 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 11% (96th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2024-21378?: CVE-2024-21378 primarily affects Microsoft 365 Apps. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2024-21378?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2024-21378 have an EU (EUVD) identifier?: Yes. CVE-2024-21378 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-19090.
When was CVE-2024-21378 published?: CVE-2024-21378 was published on 2024-02-13 and last updated on 2026-08-10.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21378

Affected products (4)

cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:*:*
cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:*:*:*
cpe:2.3:a:microsoft:outlook:2016:*:*:*:*:*:*:*

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