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Global Alert: Microsoft SharePoint Breach Exposes Sensitive Data

Microsoft has issued an urgent security warning after confirming that a serious vulnerability in its widely used SharePoint collaboration platform is being actively exploited by cyber attackers. The threat, according to security researchers and U.S. government agencies, could affect thousands of businesses and government institutions worldwide.

The breach impacts on-premises versions of SharePoint, not the cloud-based Microsoft 365, and allows attackers to gain unauthorized access to systems, execute code, and steal sensitive data. This vulnerability has prompted rapid responses from cybersecurity agencies, including the Cybersecurity and Infrastructure Security Agency (CISA).

Scope of the Breach and Microsoft’s Response

On Sunday, Microsoft confirmed that it had released patches for two versions of SharePoint. The following evening, an additional patch for SharePoint Server 2016—an older, on-premises version still used by many enterprises—was also issued.

Despite these efforts, one version of SharePoint remains unpatched, leaving organizations still exposed to risk. Microsoft has not disclosed the number of impacted users but said the threat applies exclusively to self-hosted SharePoint environments.

A Microsoft spokesperson declined to provide further comments beyond a brief statement on the company’s blog, emphasizing that customers using cloud-hosted SharePoint services remain unaffected.

CISA: Attackers Can Bypass Authentication

The Cybersecurity and Infrastructure Security Agency called the flaw “critical,” warning that it grants unauthenticated attackers access to file systems and the ability to execute arbitrary code remotely. The agency stated this level of access poses a significant national and economic risk, especially to sectors handling sensitive data.

“This vulnerability enables attackers to fully compromise SharePoint servers,” the agency noted. “We urge all organizations using affected versions to immediately apply the patches provided.”

Researchers: Attack Is Widespread and Highly Coordinated

Cybersecurity firms are raising alarms over the global scale and severity of the exploit. Palo Alto Networks’ Unit 42, which is actively tracking the campaign, believes “thousands of organizations” have already been compromised.

“The exploits are real, in-the-wild, and pose a serious threat,” said Michael Sikorski, CTO of Palo Alto Networks. “We’re seeing evidence of deep intrusions—data exfiltration, password harvesting, and persistent backdoors have already been deployed in several environments.”

In Europe, cybersecurity firm Eye Security, which first identified the flaw, added that the vulnerability may allow hackers to impersonate legitimate users even after the patch is applied. That persistence risk significantly increases the potential fallout from the breach.

Eye Security also warned that compromised SharePoint servers are often linked to other Microsoft applications like Outlook and Teams, raising the possibility of cascading breaches across enterprise networks.

Broader Impact and Unrelated IT Outage

In a possibly unrelated incident, Alaska Airlines reported a three-hour ground operations halt on Sunday due to an unspecified IT outage. The issue, resolved by 2 a.m. EST, prompted brief speculation about its link to the SharePoint breach, though no formal connection has been established.

What Organizations Need to Do Now

Experts are urging all businesses and government agencies running on-premises SharePoint servers to:

• Apply all available patches immediately
• Audit system access logs for suspicious behavior
• Isolate compromised systems and reset credentials linked to SharePoint services
• Conduct vulnerability scans to assess the depth of intrusion

Failure to act could leave systems vulnerable to data theft, malware implants, and broader network compromise, particularly as attackers move to monetize or exploit the data they've accessed.

Final Thoughts: A Wake-Up Call for On-Prem Infrastructure

This breach serves as a stark reminder of the growing vulnerabilities facing legacy, on-premises infrastructure. While many enterprises have migrated to cloud-based systems, tens of thousands still rely on on-site solutions like SharePoint Server—often without timely security updates.

The attack underscores the need for proactive cybersecurity practices, real-time monitoring, and faster patch cycles, especially in high-value software platforms.

As the investigation continues, government agencies, enterprise CISOs, and cybersecurity professionals will be watching closely—because the consequences of inaction could be devastating.

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