CVE-2026-54993 is a Microsoft Windows Media Foundation heap-based buffer overflow that can lead to Remote Code Execution. Microsoft assigns CVSS v3.1 Base 7.8 and Temporal 6.8; the vector is local, low complexity, no privileges required, and user interaction is required (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H). Microsoft reports no public disclosure and no known exploitation, with exploit code maturity listed as UNPROVEN. Because the attack is local and requires user interaction, enterprise risk is lower than for network-reachable, no-interaction vulnerabilities, but it remains relevant where users may open attacker-crafted content.

Highlights:
- CVSS scores: Base 7.8 - Temporal 6.8
- Exploit status & code maturity: Publicly Disclosed: No; Exploited: No; Exploit Code Maturity: UNPROVEN.
- Impact: Remote Code Execution with HIGH confidentiality, integrity, and availability impacts.
- Exploitation likelihood: Exploitation Less Likely; vector context is LOCAL with LOW attack complexity and USER INTERACTION REQUIRED.
- Severity for enterprise: High severity by CVSS, but real-world enterprise risk is reduced by the local attack vector and required user interaction; higher concern for endpoints where users can open untrusted files or content.
- Patch status: available; customer action required.

Affected systems:
- Windows 10 1809
- Windows 10 21H2
- Windows 10 22H2
- Windows 11 24H2
- Windows 11 25H2
- Windows 11 26H1
- Windows 11 unspecified
- Windows Server 2019
- Windows Server 2022
- Windows Server 2025