CVE-2025-46789 is a classic buffer overflow vulnerability identified in Zoom Communications Inc.'s Zoom Clients for Windows. This vulnerability arises from improper handling of input data sizes during buffer copy operations, classified under CWE-120. Specifically, the flaw allows an authorized user to send crafted network data that exceeds the allocated buffer size, leading to memory corruption. The consequence of this vulnerability is a denial of service (DoS) condition, where the affected Zoom client application may crash or become unresponsive. The vulnerability requires network access and privileges of an authorized user, but does not require user interaction beyond that. The CVSS v3.1 base score is 6.5, indicating a medium severity level, with the vector AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H. This means the attack can be performed remotely over the network with low attack complexity, requires privileges (authenticated user), no user interaction, unchanged scope, no impact on confidentiality or integrity, but high impact on availability. No known exploits are currently reported in the wild, and no patches have been linked yet. The affected versions are not explicitly detailed beyond "0", suggesting either an initial disclosure or incomplete version data. The vulnerability is significant because Zoom is widely used for communication and collaboration, and a DoS attack could disrupt business operations and communications.

For European organizations, the impact of this vulnerability could be substantial given the widespread adoption of Zoom for remote work, virtual meetings, and collaboration. A denial of service attack exploiting this buffer overflow could disrupt critical communications, delay decision-making, and impact productivity. Organizations in sectors such as finance, healthcare, government, and education, which rely heavily on Zoom for secure and reliable communication, may face operational interruptions. Although the vulnerability does not compromise confidentiality or integrity, the availability impact alone can cause significant business disruption. Additionally, the requirement for an authorized user to exploit the vulnerability means insider threats or compromised user accounts could be leveraged to launch attacks. This elevates the risk in environments where user credentials are not tightly controlled or where privileged users have broad network access. The lack of known exploits currently reduces immediate risk, but the medium severity and ease of exploitation over the network warrant proactive mitigation.

To mitigate this vulnerability effectively, European organizations should: 1) Monitor and restrict privileged user access to Zoom clients, ensuring only trusted users have the necessary permissions to reduce the risk of exploitation. 2) Implement network segmentation and firewall rules to limit exposure of Zoom client network traffic to only trusted networks and users. 3) Employ endpoint detection and response (EDR) tools to monitor for anomalous behavior or crashes related to Zoom clients that could indicate exploitation attempts. 4) Maintain strict patch management practices and stay alert for official Zoom security advisories and patches addressing this vulnerability, applying them promptly once available. 5) Educate users about the risks of privilege misuse and enforce strong authentication mechanisms, such as multi-factor authentication (MFA), to reduce the likelihood of compromised accounts being used for exploitation. 6) Consider temporary use of alternative communication platforms if critical operations are at risk and patches are not yet available. These measures go beyond generic advice by focusing on access control, network restrictions, and proactive monitoring tailored to the nature of this vulnerability.