CVE-2020-1200 in SharePoint Server
Summary
by MITRE
<p>A remote code execution vulnerability exists in Microsoft SharePoint when the software fails to check the source markup of an application package. An attacker who successfully exploited the vulnerability could run arbitrary code in the context of the SharePoint application pool and the SharePoint server farm account.</p> <p>Exploitation of this vulnerability requires that a user uploads a specially crafted SharePoint application package to an affected version of SharePoint.</p> <p>The security update addresses the vulnerability by correcting how SharePoint checks the source markup of application packages.</p>
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Analysis
by VulDB Data Team • 02/24/2026
The vulnerability described in CVE-2020-1200 represents a critical remote code execution flaw within Microsoft SharePoint platforms that stems from inadequate validation of application package markup sources. This weakness allows attackers to escalate privileges and execute malicious code with elevated permissions typically reserved for system-level operations. The vulnerability specifically impacts SharePoint environments where application packages are processed and validated, creating a pathway for adversaries to gain unauthorized access to sensitive organizational data and infrastructure resources.
This security flaw operates through a validation bypass mechanism where SharePoint fails to properly verify the integrity and source of application packages before processing them. The technical implementation involves insufficient input sanitization and markup validation routines that should normally inspect and authenticate package contents against known good patterns and security policies. When users upload maliciously crafted SharePoint application packages, the system processes these without adequate source verification, allowing attackers to inject malicious code that executes within the SharePoint application pool context. This execution context provides attackers with significant privileges that can escalate to full server farm account access, potentially compromising entire SharePoint deployments.
The operational impact of CVE-2020-1200 extends beyond simple code execution to encompass complete system compromise and data exfiltration capabilities. Attackers leveraging this vulnerability can establish persistent backdoors, modify SharePoint configurations, access confidential documents, and potentially use the compromised environment as a launchpad for lateral movement within corporate networks. The requirement for user interaction through package uploads creates a realistic attack vector that can be exploited via social engineering campaigns targeting SharePoint administrators or automated upload mechanisms within compromised environments. This vulnerability aligns with CWE-20, which describes improper input validation, and demonstrates how insufficient validation can lead to severe privilege escalation and remote code execution scenarios.
Microsoft's security update addresses this vulnerability by implementing enhanced markup validation procedures that rigorously check application package sources before processing. The fix involves strengthening the application package validation logic to ensure proper source authentication and content integrity checks, preventing malicious packages from being executed within the SharePoint environment. Organizations should prioritize immediate deployment of this security update to protect their SharePoint infrastructure from exploitation attempts. Additional mitigation strategies include implementing strict file upload restrictions, monitoring SharePoint upload activities, and conducting regular security assessments of SharePoint environments to identify potential exploitation vectors and maintain robust security postures against similar vulnerabilities. The remediation approach follows established security best practices for preventing privilege escalation through input validation failures and aligns with defensive measures recommended in the MITRE ATT&CK framework for exploitation techniques targeting web applications and server-side vulnerabilities.