SharePoint Vulnerability Exploited Shortly After PoC Release

Active exploitation has been observed for CVE-2026-55040, a weak authentication vulnerability in Microsoft SharePoint that was patched during July Patch Tuesday. The attacks began immediately following the publication of a proof-of-concept exploit by Rapid7, allowing unauthenticated remote attackers to bypass security controls and access sensitive data. This incident marks the fifth SharePoint flaw targeted this summer, prompting urgent patching recommendations from CISA.