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Microsoft Sharepoint Authentication Bypass - 20260813001

Overview

Microsoft have released a security advisory for a critical authentication bypass vulnerability in Microsoft SharePoint Server. Successful exploitation could allow an unauthorised attacker to bypass a security feature over a network and gain access to affected SharePoint environments.

What is vulnerable?

Product(s) Affected Version(s) CVE CVSS Severity
Microsoft SharePoint Server Vendor listed affected versions CVE-2026-55040 9.1 Critical

What has been observed?

The WASOC has not received any reports of exploitation of this vulnerability on Western Australian Government networks at the time of writing.

Recommendation

The WASOC recommends administrators apply the solutions as per vendor instructions to all affected devices within expected timeframes (refer Patch Management):