CVE-2026-81948 – Microsoft Excel Remote Code Execution Vulnerability

CVE-2026-81948 is a critical Microsoft Excel remote code execution vulnerability caused by a heap-based buffer overflow. An unauthorized attacker can send a specially crafted Office file and convince a user to open it, potentially allowing attacker-controlled code to execute locally. No privileges are required, but successful exploitation requires user interaction.

CVSS SCORE: 7.8.

SEVERITY: Critical.

THREAT: An attacker could use a malicious Office file to trigger a heap-based buffer overflow and execute code on an affected system. The attack has low complexity and requires no privileges, although the targeted user must open the malicious file. Successful exploitation could have a high impact on confidentiality, integrity, and availability.

EXPLOITS: This vulnerability is not publicly disclosed and is not known to be exploited. Exploitation is assessed as less likely, and exploit code maturity is listed as unproven. The source does not confirm the existence of public exploit code, zero-day exploitation, or proof-of-concept exploit code.

TECHNICAL SUMMARY: CVE-2026-81948 is a heap-based buffer overflow vulnerability (CWE-122) affecting Microsoft Excel and supported Microsoft Office products listed below. A specially crafted Office file can trigger the memory corruption condition when opened by a user. The attack vector is local, attack complexity is low, privileges are not required, and user interaction is required. Successful exploitation allows code execution locally and can result in high confidentiality, integrity, and availability impact. The Preview Pane is explicitly not an attack vector.

EXPLOITABILITY: Affected products include Microsoft 365 Apps for Enterprise (32-bit and 64-bit), Microsoft Excel 2016 (32-bit and 64-bit), Microsoft Office 2019 (32-bit and 64-bit), Microsoft Office LTSC 2021 (32-bit and 64-bit), and Microsoft Office LTSC 2024 (32-bit and 64-bit). Exploitation requires the attacker to send a malicious Office file and convince the user to open it.

BUSINESS IMPACT: Successful exploitation could allow attacker-controlled code to run on an affected endpoint, creating significant risks to sensitive information, data integrity, and system availability. In an organizational environment, a convincing malicious document could turn normal Office use into a serious endpoint compromise.

WORKAROUND: No mitigations or workarounds are specified. An official fix is identified as the remediation.

URGENCY: This vulnerability is rated Critical and can result in remote code execution with high confidentiality, integrity, and availability impact. Although exploitation is assessed as less likely and no exploitation is currently identified, affected Microsoft Office and Excel installations should receive the official fix promptly to reduce exposure to malicious Office files.