CVE-2023-21823 is an integer overflow vulnerability classified under CWE-190, affecting Microsoft Office for Android version 16.0.1. The vulnerability is located within the Windows Graphics Component used by the Office suite on Android devices. Integer overflow or wraparound occurs when arithmetic operations exceed the maximum size of an integer type, causing unexpected behavior such as memory corruption. This flaw can be exploited by a local attacker with limited privileges (AV:L, PR:L) without requiring user interaction (UI:N). Successful exploitation could lead to remote code execution, allowing the attacker to execute arbitrary code with the privileges of the affected application. The vulnerability impacts confidentiality, integrity, and availability (C:H/I:H/A:H), making it critical for data protection and system stability. The CVSS vector indicates low attack complexity (AC:L) and no user interaction is required, increasing the risk of exploitation once a local foothold is established. Although no public exploits are known at this time, the vulnerability is officially published and assigned a high severity score of 7.8. The lack of available patches at the time of reporting necessitates proactive mitigation strategies. The vulnerability's root cause is improper input validation or arithmetic handling within the graphics processing routines of the Office app, which could be triggered by specially crafted files or data processed locally on the device.

For European organizations, this vulnerability poses a significant risk, especially for those relying on Microsoft Office for Android in mobile or remote work environments. Exploitation could lead to unauthorized code execution, potentially allowing attackers to access sensitive corporate data, manipulate documents, or disrupt business operations. The compromise of confidentiality, integrity, and availability could affect sectors such as finance, healthcare, government, and critical infrastructure. Given the local attack vector, insider threats or compromised devices could be leveraged to exploit this vulnerability. The lack of user interaction requirement means that once local access is gained, exploitation can be automated or triggered silently. This elevates the threat level for organizations with Bring Your Own Device (BYOD) policies or less controlled mobile environments. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the potential for future attacks, especially as threat actors develop proof-of-concept exploits.

Organizations should implement the following specific mitigations: 1) Monitor Microsoft’s security advisories closely and apply patches or updates for Microsoft Office for Android as soon as they become available. 2) Restrict local access to Android devices running vulnerable Office versions by enforcing strong device authentication and limiting physical access. 3) Employ mobile device management (MDM) solutions to control app installations, enforce security policies, and remotely wipe compromised devices. 4) Educate users on the risks of installing untrusted applications or opening suspicious files on their mobile devices. 5) Implement application whitelisting and sandboxing to limit the impact of potential exploitation. 6) Monitor device logs and network traffic for unusual activity that could indicate exploitation attempts. 7) Consider disabling or limiting the use of Microsoft Office for Android in high-risk environments until patches are applied. 8) Use endpoint detection and response (EDR) tools capable of detecting anomalous behavior on mobile devices. These measures go beyond generic advice by focusing on controlling local access, device management, and proactive monitoring tailored to the mobile context.