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CVE-2026-58644 and CVE-2026-50522 affecting SharePoint Server

This section contains time sensitive announcements about specific cyber threats, vulnerabilities and scams. Each alert has information you need to be aware of, and what actions to take to mitigate any risk to you or your organisation.

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4:00PM, 17 July 2026

TLP Rating: Clear

CVE-2026-58644 and CVE-2026-50522 affecting SharePoint Server

Two critical vulnerabilities in Microsoft SharePoint are under active exploitation.

Both CVE-2026-58644 and CVE-2026-50522 are deserialization of untrusted data vulnerabilities which can enable an unauthorised attacker to execute code over a network.

The NCSC encourages organisations in New Zealand that use affected versions of the products to review the vendor advisory and apply the remediation as soon as possible.

What's happening

Systems affected

CVE-2026-58644 affects the following products:

  • Microsoft SharePoint Server 2019 16.0.0 before 16.0.10417.20153
  • Microsoft SharePoint Enterprise Server 2016 16.0.0 before 16.0.5556.1005
  • Microsoft SharePoint Server Subscription Edition 16.0.0 before 16.0.19725.20384

 CVE-2026-50522 affects the following products:

  • Microsoft SharePoint Server 2019 16.0.0 before 16.0.10417.20175
  • Microsoft SharePoint Enterprise Server 2016 16.0.0 before 16.0.5561.1001
  • Microsoft SharePoint Server Subscription Edition 16.0.0 before 16.0.19725.20434

What to do

Prevention

To prevent exploitation, update affected products to a patched version. If remediation or mitigation action cannot be undertaken immediately, then we recommend isolating SharePoint from the internet.

More information

Read more about this alert on the vendor website:

CVE-2026-58644 - Security Update Guide - Microsoft - Microsoft SharePoint Remote Code Execution Vulnerability  External Link

External Link External Link

CVE-2026-50522 - Security Update Guide - Microsoft - Microsoft SharePoint Remote Code Execution Vulnerability External Link

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