CVE-2025-21397
Published: 11 February 2025
Summary
CVE-2025-21397 is a high-severity Use After Free (CWE-416) vulnerability in Microsoft Office Long Term Servicing Channel. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked in the top 42.6% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-2 (Flaw Remediation) and SI-16 (Memory Protection).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
SI-2 requires timely identification, reporting, and correction of system flaws, directly addressing this use-after-free vulnerability through application of Microsoft security updates.
SI-16 implements memory protection mechanisms like ASLR and DEP that mitigate exploitation of use-after-free vulnerabilities by preventing reliable code execution.
SI-3 deploys malicious code protection at endpoints to scan and block malicious Office documents that exploit this remote code execution vulnerability.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CVE describes client-side RCE in Microsoft Office via use-after-free, exploited by tricking user to open malicious document; directly maps to exploitation for client execution and user execution of malicious file.
NVD Description
Microsoft Office Remote Code Execution Vulnerability
Deeper analysisAI
CVE-2025-21397 is a remote code execution vulnerability in Microsoft Office, classified under CWE-416 (use-after-free) with additional details under NVD-CWE-noinfo. Published on 2025-02-11T18:15:38.293, it carries a CVSS v3.1 base score of 7.8 (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H), indicating high severity due to its potential for significant impact despite requiring local access and user interaction.
An attacker with local access can exploit this vulnerability with low complexity and no required privileges by tricking a user into performing an action, such as opening a malicious Office document. Successful exploitation enables arbitrary code execution on the target system, resulting in high impacts to confidentiality, integrity, and availability.
Microsoft's advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-21397 provides guidance on mitigation, including the application of security updates to affected Microsoft Office versions.
Details
- CWE(s)