CVE-2026-26110 – Microsoft Office Remote Code Execution Vulnerability

This vulnerability in Microsoft Office allows an attacker to execute arbitrary code due to a type confusion flaw (CWE-843). The issue occurs when the application accesses a resource using an incompatible data type, causing incorrect memory handling. If exploited, the vulnerability could allow attackers to run malicious code on the affected system with the privileges of the logged-in user. The Preview Pane can act as an attack vector, meaning the vulnerability may be triggered simply by previewing a malicious Office document.

CVSS Score: 8.4
SEVERITY: High

THREAT:
This vulnerability allows attackers to execute arbitrary code locally without requiring privileges or user interaction. Because the flaw involves memory mismanagement, attackers can potentially manipulate program execution to run malicious payloads. If exploited in corporate environments, attackers could gain control of systems, deploy malware, or use compromised machines as entry points for further network attacks.

EXPLOITS:
At the time of publication, there are no confirmed public exploits or proof-of-concept code available. Microsoft reports that the vulnerability has not been publicly disclosed and is not currently being exploited in the wild. Exploit code maturity is listed as unproven, and the exploitability assessment indicates exploitation is less likely.

TECHNICAL SUMMARY:
The vulnerability results from a type confusion condition within Microsoft Office. Type confusion occurs when a program mistakenly treats a memory object as a different data type than it actually is. This can cause the application to perform invalid operations on memory structures, potentially leading to memory corruption. Attackers can exploit this condition by crafting specially designed Office documents that trigger incorrect object handling when processed by the application. When the vulnerability is triggered, the attacker may redirect program execution to run arbitrary code.

EXPLOITABILITY:
This vulnerability affects Microsoft Office installations. The attack vector is local, meaning the malicious content must be executed or processed on the target machine. The Preview Pane can trigger the vulnerability when a specially crafted Office document is previewed, enabling the attack without fully opening the file.

BUSINESS IMPACT:
Remote code execution vulnerabilities in Office applications pose serious risks for organizations because documents are widely exchanged through email, file shares, and collaboration platforms. If exploited, attackers could gain control of user systems, deploy ransomware, steal corporate data, or move laterally across internal networks. A single malicious document could compromise an endpoint and provide attackers with a foothold inside the organization.

WORKAROUND:
If immediate patching is not possible, organizations should disable the Preview Pane in file explorers and restrict the opening or previewing of Office documents from untrusted sources. Implementing strong email filtering and endpoint protection can also help reduce exposure to malicious files.

URGENCY:
This vulnerability enables arbitrary code execution without privileges or user interaction and can be triggered through document previewing. Because Office documents are a common delivery mechanism for attacks, delaying patch deployment increases the risk that attackers could weaponize the flaw once technical details become widely known.