CVE-2021-38656
CVE-2021-38656 is a high-severity vulnerability in Microsoft 365 Apps with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-416.
Key facts
- Severity: High (CVSS 3.x base score 7.8)
- CVSS v2: 6.8
- EPSS exploit prediction: 5% (91st percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-416
- Affected product: Microsoft 365 Apps
- Published:
- Last modified:
Description
Microsoft Word Remote Code Execution Vulnerability
Frequently asked questions
- What is CVE-2021-38656?
- Microsoft Word Remote Code Execution Vulnerability
- How severe is CVE-2021-38656?
- CVE-2021-38656 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2021-38656 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (91st percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-38656?
- CVE-2021-38656 affects Microsoft 365 Apps. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2021-38656?
- 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.
- When was CVE-2021-38656 published?
- CVE-2021-38656 was published on 2021-09-15 and last updated on 2026-06-17.
References
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-38656
- https://www.zerodayinitiative.com/advisories/ZDI-21-1082/
Affected products (1)
- cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:*:*
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-416 (Use After Free) vulnerabilities
- CVE-2026-13782 — Critical (CVSS 10.0): Use after free in Browser in Google Chrome prior to 150.0.7871.47 allowed a remote attacker who had compromised the…
- CVE-2026-4725 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149…
- CVE-2026-4688 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox…
- CVE-2025-24085 — Critical (CVSS 10.0): A use after free issue was addressed with improved memory management. This issue is fixed in iOS 18.3 and iPadOS 18.3,…
- CVE-2024-43102 — Critical (CVSS 10.0): Concurrent removals of certain anonymous shared memory mappings by using the UMTX_SHM_DESTROY sub-request of…
- CVE-2021-32495 — Critical (CVSS 10.0): Radare2 has a use-after-free vulnerability in pyc parser's get_none_object function. Attacker can read freed memory…