SharePoint authentication bypass CVE-2026-55040 exploited after PoC
Source headline: Attackers Exploit SharePoint Authentication Bypass After Public PoC Release
Intelligence Summary
Threat actors began exploiting a Microsoft SharePoint authentication bypass after a proof-of-concept was released. The flaw is tracked as CVE-2026-55040 with a CVSS score of 9.1. Microsoft patched the vulnerability in its July 2026 Patch Tuesday updates. The issue is described as a security feature bypass caused by weak authentication. Because attackers are already using a public PoC, organizations using SharePoint should apply the July 2026 patches immediately.
Recommended Action
Check your exposure to CVE-2026-55040 (CVSS 9.1) and apply the vendor fix once available. Until then, watch authentication and outbound traffic logs for the indicators described in the source. This signal rests on a single report, so corroborate it before acting on anything irreversible.