VulnHub

Real-time Cybersecurity News

Critical

CISA Adds Exploited SharePoint RCE Zero-Day CVE-2026-58644 to KEV

The Hacker News
Actively Exploited
CVEZero-dayMicrosoftVulnerabilityRCECritical

Overview

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added a critical vulnerability in Microsoft SharePoint Server to its list of Known Exploited Vulnerabilities. This flaw, identified as CVE-2026-58644, has a high severity score of 9.8, indicating that it poses a significant risk. Federal Civilian Executive Branch agencies are mandated to implement necessary patches by July 19, 2026. The vulnerability involves a deserialization issue that could allow attackers to execute remote code on affected systems, making it crucial for organizations using SharePoint to take immediate action. By addressing this vulnerability, agencies can help prevent potential exploitation by malicious actors.

Key Takeaways

  • Active Exploitation: This vulnerability is being actively exploited by attackers. Immediate action is recommended.
  • Affected Systems: Microsoft SharePoint Server
  • Action Required: Federal Civilian Executive Branch agencies must apply the fixes by July 19, 2026.
  • Timeline: Newly disclosed

Original Article Summary

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Thursday added a newly patched security flaw impacting Microsoft SharePoint Server to its Known Exploited Vulnerabilities (KEV) catalog, requiring Federal Civilian Executive Branch (FCEB) agencies to apply the fixes by July 19, 2026. The vulnerability in question is CVE-2026-58644 (CVSS score: 9.8), a critical deserialization

Impact

Microsoft SharePoint Server

Exploitation Status

This vulnerability is confirmed to be actively exploited by attackers in real-world attacks. Organizations should prioritize patching or implementing workarounds immediately.

Timeline

Newly disclosed

Remediation

Federal Civilian Executive Branch agencies must apply the fixes by July 19, 2026.

Additional Information

This threat intelligence is aggregated from trusted cybersecurity sources. For the most up-to-date information, technical details, and official vendor guidance, please refer to the original article linked below.

Related Topics: This incident relates to CVE, Zero-day, Microsoft, and 3 more.

Read Original Article

Related Coverage

ShadowPad Malware Actively Exploits WSUS Vulnerability for Full System Access

The Hacker News

The ShadowPad malware is exploiting a recently patched vulnerability in Microsoft Windows Server Update Services (WSUS), identified as CVE-2025-59287, allowing attackers to gain full system access. This exploitation highlights the critical need for organizations to promptly apply security updates to vulnerable systems to prevent unauthorized access.

Nov 24, 2025

⚡ Weekly Recap: Fortinet Exploit, Chrome 0-Day, BadIIS Malware, Record DDoS, SaaS Breach & More

The Hacker News

This week, significant cybersecurity threats emerged as hackers exploited new 0-day vulnerabilities in Fortinet and Chrome, infiltrating supply chains and SaaS tools. The rapid response from major companies like Microsoft, Salesforce, and Google highlights the severity of these attacks and the ongoing challenges in securing trusted applications and software updates.

Nov 24, 2025

Microsoft Highlights Security Risks Introduced by New Agentic AI Feature

SecurityWeek

Microsoft has raised concerns about the security risks associated with its new Agentic AI feature, highlighting the potential for AI agents to engage in malicious activities like data exfiltration and malware installation if not properly secured. This underscores the critical need for robust security controls to mitigate these risks.

Nov 24, 2025

ToddyCat’s New Hacking Tools Steal Outlook Emails and Microsoft 365 Access Tokens

The Hacker News

ToddyCat, a threat actor, has developed a new tool called TCSectorCopy to steal Outlook emails and Microsoft 365 access tokens by exploiting the OAuth 2.0 authorization protocol through users' browsers. This poses a significant threat to corporate email security, as it allows unauthorized access to sensitive information outside the compromised infrastructure.

Nov 25, 2025

Microsoft: Security keys may prompt for PIN after recent updates

BleepingComputer

Microsoft has alerted users that FIDO2 security keys may require a PIN for sign-in following recent Windows updates since September 2025. This change could affect user experience and security practices, particularly for those relying on these security keys for authentication.

Nov 26, 2025

Microsoft to secure Entra ID sign-ins from script injection attacks

BleepingComputer

Microsoft is set to enhance the security of its Entra ID authentication system to protect against external script injection attacks starting in mid-to-late October 2026. This improvement aims to mitigate potential vulnerabilities that could be exploited by attackers to compromise user sign-ins.

Nov 26, 2025