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CISA: Microsoft SharePoint flaw now exploited in ransomware attacks

CISA confirmed today that ransomware gangs have begun abusing a high-severity Microsoft SharePoint remote code execution vulnerability, which has been flagged as actively exploited since early July.

What happened

Recent reporting highlighted cisa: microsoft sharepoint flaw now exploited in ransomware attacks. CISA confirmed today that ransomware gangs have begun abusing a high-severity Microsoft SharePoint remote code execution vulnerability, which has been flagged as actively exploited since early July. Tracked as CVE-2026-45659, this security flaw stems from a deserialization of untrusted data weakness and allows attackers with low privileges to execute arbitrary code on unpatched SharePoint servers.

Why it matters

This matters because it has practical implications for defensive prioritisation, exposure management, or incident response rather than sitting as abstract security commentary. KEV-style urgency also pushes the item closer to immediate operational response than routine tracking.

Assessment

The strongest signal here is that a vulnerability class or attack path is being treated as operationally relevant rather than background technical debt. In practice, that means operators should read this as a broader signal over noise item rather than a narrow one-off.

  • Review whether the issue, advisory, or attack pattern is relevant to your environment, suppliers, or exposed systems
  • Patch, harden, or validate logging and monitoring coverage where applicable
  • Monitor follow-on reporting or primary-source updates for scope expansion, implementation guidance, or stronger enforcement signals

Further reading