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 95th 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% (95th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2024-19090
- Weakness: CWE-94
- Affected product: Microsoft 365 Apps
- Published:
- Last modified:
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% (95th 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 2026-06-17.
References
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:*:*:*:*:*:*:*
More vulnerabilities in Microsoft 365 Apps
- CVE-2024-21413 — Critical (CVSS 9.8): Microsoft Outlook Remote Code Execution Vulnerability
- CVE-2023-23397 — Critical (CVSS 9.8): Microsoft Outlook Elevation of Privilege Vulnerability
- CVE-2020-0901 — Critical (CVSS 9.8): A remote code execution vulnerability exists in Microsoft Excel software when the software fails to properly handle…
- CVE-2023-33150 — Critical (CVSS 9.6): Microsoft Office Security Feature Bypass Vulnerability
- CVE-2026-40420 — High (CVSS 8.8): Use after free in Microsoft Office allows an authorized attacker to elevate privileges locally.
- CVE-2026-35436 — High (CVSS 8.8): Use after free in Microsoft Office allows an authorized attacker to elevate privileges locally.
All CVEs affecting Microsoft 365 Apps →
Other CWE-94 (Code Injection) vulnerabilities
- CVE-2026-57624 — Critical (CVSS 10.0): Unauthenticated Remote Code Execution (RCE) in Blocksy Companion Pro <= 2.1.46 versions.
- CVE-2026-10134 — Critical (CVSS 10.0): IBM Langflow OSS 1.0.0 through 1.9.3 allows an attacker to read every secret available to the Langflow process, read…
- CVE-2026-53576 — Critical (CVSS 10.0): Kestra is an open-source, event-driven orchestration platform. Prior to 1.0.45 and 1.3.21, the authentication filter…
- CVE-2026-10561 — Critical (CVSS 10.0): IBM Langflow OSS 1.0.0 through 1.9.3 has an vulnerability due to an improper isolation of Python execution combined…
- CVE-2026-25470 — Critical (CVSS 10.0): Improper Control of Generation of Code ('Code Injection') vulnerability in ACPT ACPT (Pro) - Custom Post Types Plugin…
- CVE-2026-48836 — Critical (CVSS 10.0): Unauthenticated Remote Code Execution (RCE) in Easy Invoice <= 2.1.19 versions.