In recent developments, Microsoft has taken significant steps to address critical security vulnerabilities within its SharePoint software, specifically targeting on-premises versions of their platform. The company announced security patches for a serious flaw that is actively being exploited and provided details on a newly discovered issue that has met with robust corrective measures.
Understanding the Vulnerability Landscape
On July 18, 2025, Microsoft disclosed that it was aware of ongoing attacks exploiting a vulnerability in SharePoint Server, which primarily affects on-premises installations. Known as CVE-2025-53770, this critical security flaw has been assigned a CVSS score of 9.8, indicating a high level of risk. The vulnerability is characterized by a case of remote code execution (RCE) that results from the deserialization of untrusted data. Essentially, malicious actors can potentially exploit this weak point to take control of affected systems, executing arbitrary code and thereby gaining unauthorized access to sensitive information.
This is particularly concerning given that SharePoint is often utilized in organizational environments to facilitate collaboration and store vital data, making it a prime target for cybercriminal activities.
Newly Disclosed Spoofing Flaw
Alongside the urgent need to address CVE-2025-53770, Microsoft disclosed another vulnerability—CVE-2025-53771, which deals with a spoofing issue. This flaw has a CVSS score of 6.3 and was uncovered by an anonymous researcher. The spoofing vulnerability stems from an "improper limitation of a pathname to a restricted directory" within Microsoft SharePoint, allowing an authorized attacker to perform network spoofing.
Herein lies a significant risk, as unauthorized users could masquerade as legitimate users, potentially compromising data integrity and security protocols. Microsoft’s advisory underscores the gravity of addressing both vulnerabilities, given their interconnected nature with other documented flaws, such as CVE-2025-49704 and CVE-2025-49706.
The Broader Threat Landscape
The ongoing exploitation related to these vulnerabilities has implications for various organizations, including those in sectors such as banking, education, and government. Reports indicate that at least 54 organizations have already been compromised, as cybercriminals capitalize on the weaknesses within Microsoft’s framework. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added CVE-2025-53770 to its Known Exploited Vulnerabilities (KEV) catalog, mandating that federal agencies apply the necessary security patches promptly.
In light of these revelations, it’s evident that organizations operating on-premises Microsoft SharePoint servers need to prioritize their security posture. Notably, Microsoft has recommended that customers utilize supported versions of SharePoint Server, including 2016, 2019, and the SharePoint Subscription Edition, to mitigate potential attacks effectively.
Mitigation Strategies
Organizations are urged to implement a robust array of security measures to safeguard their infrastructures. Recommendations include:
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Updating Software Regularly: Ensure that the most recent security updates are applied promptly. This will help protect against known vulnerabilities, particularly before they can be exploited by threat actors.
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Leveraging Security Tools: Enabling the Antimalware Scan Interface (AMSI) in Full Mode is crucial for optimal protection. Complementing this with effective antivirus solutions, such as Microsoft Defender, creates multiple layers of security.
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Implementing Endpoint Protection: Using Microsoft Defender for Endpoint or other equivalent threat solutions can enhance overall cybersecurity resilience, providing real-time monitoring and threat detection capabilities.
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Rotating Machine Keys: Following the application of updates, it is vital to rotate ASP.NET machine keys and perform a restart of the Internet Information Services (IIS) across all SharePoint servers to further secure the environment. This additional step significantly reduces the attack surface.
The Chain of Vulnerabilities
Furthermore, Microsoft highlighted that CVE-2025-53770 and CVE-2025-53771 are closely related to other previously identified vulnerabilities (CVE-2025-49704 and CVE-2025-49706). This relationship implies that threat actors could leverage a ‘chain’ of vulnerabilities to achieve remote code execution. The need for a multi-faceted response to such interconnected vulnerabilities is imperative. A holistic approach, rather than piecemeal fixes, is essential for maintaining a secure operational framework.
The Call to Action from Cybersecurity Experts
Industry experts have voiced serious concerns regarding the implications of these vulnerabilities. For instance, Michael Sikorski, Chief Technology Officer at Palo Alto Networks, underscored that attackers have been known to bypass identity controls, such as multi-factor authentication (MFA) and single sign-on (SSO), to gain privileged access to sensitive environments. Once attackers establish a foothold in a network, they can exfiltrate data, deploy persistent backdoors, and compromise additional assets across the organization’s digital landscape.
Sikorski’s comments reflect a crucial truth in cybersecurity: vulnerabilities within widely used applications like SharePoint present a significant risk not only to the immediate systems but potentially to entire organizational networks. With the deep integration of SharePoint with other Microsoft services—such as Office, Teams, OneDrive, and Outlook—an attacker who compromises SharePoint has multiple avenues for further intrusion.
Immediate Precautions to Consider
In light of this potential for widespread compromise, cybersecurity professionals advise immediate precautionary measures. For organizations that expose their SharePoint instances to the internet, shutting down those connections while patches are being applied is a critical step. The rapid response could greatly reduce the risk of data breaches and unauthorized access.
Moreover, organizations must foster a culture of awareness around cybersecurity issues. Employees should be educated about potential phishing attacks, social engineering schemes, and the importance of adhering to security protocols.
Conclusion: The Bigger Picture
The issue at hand transcends just the technical aspects of vulnerability management; it signifies a broader narrative about the importance of vigilance in the world of IT security. As organizations grow increasingly reliant on collaborative platforms like SharePoint, the repercussions of not addressing vulnerabilities can have far-reaching consequences.
Being proactive rather than reactive is the mantra for cybersecurity. Updating software, implementing robust security measures, and fostering an organizational culture that prioritizes cybersecurity will be crucial in combating the escalating threats posed by increasingly sophisticated adversaries.
In a world where data breaches are becoming alarmingly common, vigilance is not just a recommendation; it is an essential business strategy. Organizations must leverage the tools and available resources to protect their infrastructures and preserve the trust and safety of their users. The vulnerability landscape is dynamic, and so must be our response to it.
