CVE-2025-26639 is a high-severity integer overflow or wraparound vulnerability identified in the Windows USB Print Driver component of Microsoft Windows Server 2022 (build 10.0.20348.0). The vulnerability arises from improper handling of integer values within the USB Print Driver, which can lead to an integer overflow or wraparound condition. This flaw can be exploited by an attacker with authorized local access and low privileges to escalate their privileges on the affected system. Specifically, the attacker can leverage this vulnerability to execute code with elevated privileges, potentially gaining SYSTEM-level access. The vulnerability does not require user interaction and has a low attack complexity, but it does require the attacker to have some level of local access (local vector with low privileges). The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability, as successful exploitation could allow full control over the affected server. No known exploits are currently reported in the wild, and no patches have been linked yet, indicating that mitigation may rely on workarounds or upcoming vendor updates. The vulnerability is categorized under CWE-190 (Integer Overflow or Wraparound), which typically involves arithmetic operations exceeding the maximum value storable in a variable, leading to unexpected behavior or memory corruption. Given the component involved (USB Print Driver), exploitation likely involves interaction with USB print devices or related driver interfaces.

For European organizations, this vulnerability poses a significant risk, especially for enterprises and data centers relying on Windows Server 2022 for critical infrastructure and print services. Successful exploitation could lead to unauthorized privilege escalation, allowing attackers to bypass security controls, access sensitive data, manipulate system configurations, or deploy malware with elevated rights. This could disrupt business operations, compromise data confidentiality and integrity, and potentially lead to widespread network compromise if the server is part of a larger domain or cloud infrastructure. Organizations in sectors such as finance, healthcare, government, and manufacturing—where Windows Server 2022 adoption is common—may face operational and reputational damage. The local attack vector means that insider threats or attackers who gain initial foothold through other means (e.g., phishing, compromised credentials) could leverage this vulnerability to deepen their access. The lack of user interaction requirement increases the risk of automated or stealthy exploitation once local access is obtained.

European organizations should prioritize the following mitigation steps: 1) Monitor for official Microsoft security advisories and apply patches immediately once available, as no patch is currently linked. 2) Restrict local access to Windows Server 2022 systems, enforcing strict access controls and monitoring for unauthorized logins or privilege escalations. 3) Implement application whitelisting and endpoint detection and response (EDR) solutions to detect anomalous behavior related to USB print driver usage or privilege escalation attempts. 4) Disable or restrict USB print driver usage on servers where printing is not essential, or use group policies to limit driver installation and usage. 5) Conduct regular privilege audits and minimize the number of users with local privileges to reduce the attack surface. 6) Employ network segmentation to isolate critical servers and limit lateral movement opportunities. 7) Educate IT staff about the vulnerability and encourage vigilance for suspicious activity related to USB devices or print services. These targeted measures go beyond generic advice by focusing on controlling the specific attack vector and reducing exposure to local privilege escalation.