CVE-2020-1453 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-2020-1453 represents a critical remote code execution flaw within Microsoft SharePoint platforms that stems from inadequate validation of application package markup sources. This weakness specifically affects SharePoint versions where the software fails to properly verify the integrity and origin of application packages before processing them. The vulnerability creates a pathway for attackers to execute malicious code with elevated privileges, as successful exploitation allows execution in the context of the SharePoint application pool and the SharePoint server farm account, which typically possess extensive system permissions. The flaw exists in the validation mechanism that should ensure application packages originate from trusted sources and contain legitimate markup structures before being deployed within the SharePoint environment.
The technical nature of this vulnerability aligns with CWE-22, which addresses improper limitation of a pathname to a restricted directory, and CWE-434, which covers insecure upload of file with dangerous type. The attack vector requires a user to upload a specially crafted application package to an affected SharePoint instance, making this a user interaction dependent vulnerability that can be exploited through social engineering or by compromising user accounts with upload privileges. The exploitation process leverages the insufficient input validation to bypass normal security boundaries, allowing attackers to inject malicious code that executes within the SharePoint application context. This type of vulnerability is particularly dangerous because it operates at the application layer and can potentially provide attackers with persistent access to the SharePoint infrastructure.
The operational impact of CVE-2020-1453 extends beyond immediate code execution capabilities to encompass broader system compromise potential. When exploited, the vulnerability enables attackers to gain access to the SharePoint server farm account, which typically possesses administrative privileges across the entire SharePoint farm. This level of access allows for complete system compromise including data exfiltration, lateral movement within the network, and potential escalation to other systems. The vulnerability affects SharePoint Server 2016 and SharePoint Server 2019 versions, making it relevant to organizations running these platforms. The attack requires minimal user interaction beyond the initial upload, making it particularly dangerous in environments where users have upload capabilities or where administrative accounts are compromised.
Organizations should implement multiple layers of defense to mitigate this vulnerability effectively. The primary recommended mitigation involves applying the official Microsoft security update that addresses the markup validation issue in SharePoint application package processing. Additionally, administrators should implement strict access controls limiting who can upload application packages to SharePoint environments and consider implementing application whitelisting policies to prevent execution of unauthorized code. Network segmentation and monitoring solutions should be deployed to detect unusual upload activities or attempts to execute code within SharePoint environments. The vulnerability demonstrates the importance of input validation and source verification in preventing privilege escalation attacks, aligning with ATT&CK technique T1059 for command and script interpreter usage and T1078 for valid accounts. Regular security assessments and penetration testing should be conducted to identify similar validation weaknesses in other applications within the SharePoint ecosystem and broader infrastructure.