CVE-2025-3770: 
Linux Debian vulnerability analysis and mitigation

A critical vulnerability (CVE-2025-53770) has been identified in on-premises Microsoft SharePoint Server that allows unauthorized attackers to execute code over a network through deserialization of untrusted data. The vulnerability was discovered and disclosed on July 19, 2025, affecting multiple versions of SharePoint Server including SharePoint Server 2019, SharePoint Server 2016 Enterprise, and SharePoint Server Subscription Edition versions up to 16.0.18526.20508. Microsoft has confirmed that this vulnerability is actively being exploited in the wild (Microsoft Advisory).

The vulnerability is classified as a deserialization of untrusted data issue (CWE-502) with a CVSS v3.1 base score of 9.8 (CRITICAL), indicating maximum severity across confidentiality, integrity, and availability impacts. The attack vector is network-based (AV:N) with low attack complexity (AC:L), requiring no privileges (PR:N) or user interaction (UI:N) (Microsoft Advisory).

The exploitation of this vulnerability allows attackers to execute arbitrary code with system privileges on affected SharePoint servers. This can lead to complete system compromise, potentially affecting data confidentiality, integrity, and availability of the SharePoint infrastructure (CISA Alert).

While Microsoft prepares a comprehensive patch, they have released interim mitigation guidance. CISA recommends disconnecting public-facing versions of SharePoint Server that have reached EOL/EOS, including SharePoint Server 2013 and earlier versions. For supported versions, organizations should configure AMSI integration in SharePoint and deploy Defender AV on all SharePoint servers (CISA Alert, Microsoft Blog).

The security community has responded with significant concern to this vulnerability, particularly due to its high severity rating and active exploitation. Security researchers and organizations worldwide are tracking the exploitation attempts, with Shadowserver Foundation providing regular updates on the attack patterns (Shadowserver). The vulnerability has garnered extensive media coverage, highlighting the urgency of implementing mitigations (Forbes, Ars Technica).