This vulnerability allows unauthorized attackers to execute code locally due to improper input validation in Microsoft Office SharePoint. With a CVSS score of 7.8, this high-severity issue can lead to significant risks if left unaddressed. The exploitation status indicates no known exploits, but the potential for local code execution remains a concern for organizations using affected versions of SharePoint.
Organizations using Microsoft SharePoint should assess their installations immediately. The vulnerability affects multiple versions, including SharePoint Server 2016 and 2019. The urgency for defenders is high, as attackers may leverage this vulnerability to execute arbitrary code, potentially leading to data breaches or system compromises.
Given the severity and potential impact, organizations should prioritize patching immediately. Ensuring that all systems are updated to the latest versions will help mitigate the risks associated with this vulnerability and protect sensitive information from unauthorized access.
The vulnerability was published on January 13, 2026, and has been analyzed thoroughly. It is crucial for organizations to stay informed about such vulnerabilities and take proactive measures to secure their systems.
Vulnerability Details
The official description states that improper input validation in Microsoft Office SharePoint allows an unauthorized attacker to execute code locally. The vulnerability is categorized as CWE-20, which pertains to improper input validation. The CVSS score of 7.8 indicates high severity, with confidentiality, integrity, and availability impacts all rated as high.
Affected versions include SharePoint Server 2016 and 2019, with specific criteria defined for vulnerable configurations. Organizations should ensure they are running the latest versions to avoid exploitation.
Technical Analysis
The root cause of this vulnerability is improper input validation, which enables local code execution. The attack vector is local, requiring an attacker to have access to the target system to exploit the vulnerability. The attack complexity is low, meaning that successful exploitation does not require significant skill or resources.
No privileges are required for exploitation, but user interaction is necessary. The impacts on confidentiality, integrity, and availability are all rated high, indicating that successful exploitation can have severe consequences for affected organizations.
Risk & Impact Analysis
Risk to organizations includes potential unauthorized access to sensitive data and the ability to execute arbitrary code. The blast radius is significant, as multiple versions of SharePoint are affected. Given the CVSS score of 7.8, organizations should address this vulnerability in their priority patch cycle.
The urgency is high due to the potential for local exploitation and the critical nature of the data often managed by SharePoint. Organizations should schedule remediation as soon as possible to mitigate these risks.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
Affected versions include: SharePoint Server 2016 and SharePoint Server 2019, with specific configurations listed. Organizations should ensure they are using versions beyond 16.0.19127.20442 to mitigate this vulnerability.
Mitigation & Remediation
Organizations should prioritize applying patches provided by Microsoft to remediate this vulnerability. If a patch is not immediately available, consider implementing workarounds such as restricting access to affected systems until updates can be applied. Configuration hardening should also be reviewed to minimize the attack surface.
For ongoing security, organizations may want to engage in penetration testing to identify similar weaknesses and ensure their systems are secure.
Detection Guidance
To detect potential exploitation of this vulnerability, organizations should monitor for unusual behavior in SharePoint logs, particularly around user interactions that could indicate attempts to execute unauthorized code. Additionally, network signatures that signal local access attempts should be established.
AppSecure Threat Intelligence Insight
This vulnerability highlights the importance of robust input validation within applications. Organizations should prioritize reviewing their input validation processes to prevent similar vulnerabilities in the future.
Regular security assessments can help organizations identify and mitigate risks associated with vulnerabilities like CVE-2026-20951. For best practices, teams can refer to our comprehensive guide on vulnerability management programs.
In conclusion, the threat landscape continues to evolve, and organizations must remain vigilant in their security practices to protect against such vulnerabilities.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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