CVE-2026-20948 is a vulnerability classified under CWE-822 (Untrusted Pointer Dereference) affecting Microsoft SharePoint Enterprise Server 2016, specifically version 16.0.0. The root cause lies in how Microsoft Office Word components handle pointers when processing certain documents, leading to the possibility of dereferencing untrusted pointers. This flaw can be exploited by an attacker who crafts a malicious Word document that, when opened by a user within the SharePoint environment, triggers the vulnerability and allows execution of arbitrary code locally on the victim's machine. The attack vector is local (AV:L), requiring user interaction (UI:R) but no privileges (PR:N), and the attack complexity is low (AC:L). The vulnerability impacts confidentiality, integrity, and availability at a high level (C:H/I:H/A:H), meaning an attacker could gain full control over the affected system, steal sensitive data, modify or delete information, or disrupt services. Although no known exploits are currently active in the wild and no official patches have been released, the vulnerability is publicly disclosed and rated with a CVSS 3.1 score of 7.8, indicating a high risk. The vulnerability's presence in SharePoint 2016 is particularly concerning given SharePoint's widespread use in enterprise collaboration and document management, making it a valuable target for attackers seeking to compromise organizational networks through trusted document workflows.

For European organizations, the impact of CVE-2026-20948 could be substantial. SharePoint Enterprise Server 2016 is widely deployed across various sectors including government, finance, healthcare, and manufacturing, all of which handle sensitive and regulated data. Exploitation could lead to unauthorized code execution, enabling attackers to escalate privileges, move laterally within networks, exfiltrate confidential information, or disrupt critical business operations. This could result in data breaches violating GDPR requirements, financial losses, reputational damage, and operational downtime. The requirement for user interaction means phishing or social engineering campaigns could be used to deliver malicious documents, increasing the risk. The lack of current patches means organizations must rely on interim mitigations to reduce exposure. Given the high confidentiality, integrity, and availability impact, the threat is particularly acute for organizations with stringent compliance obligations and critical infrastructure dependencies on SharePoint services.

1. Immediately implement strict email and document filtering policies to block or quarantine suspicious Word documents, especially those originating from untrusted or external sources. 2. Educate users about the risks of opening unsolicited or unexpected documents, emphasizing caution with files received via email or collaboration platforms. 3. Restrict SharePoint document upload permissions to trusted users and enforce content validation policies to detect potentially malicious files. 4. Employ application whitelisting and endpoint protection solutions capable of detecting unusual behaviors associated with exploitation attempts. 5. Monitor SharePoint and endpoint logs for indicators of compromise or anomalous activities related to document processing. 6. Prepare for rapid deployment of official patches or updates from Microsoft once they become available, including testing in controlled environments. 7. Consider isolating or segmenting SharePoint servers to limit lateral movement in case of compromise. 8. Regularly back up critical SharePoint data and verify restoration procedures to minimize impact from potential attacks. 9. Engage with Microsoft support and threat intelligence sources to stay informed about developments related to this vulnerability.