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A critical Microsoft SharePoint remote code execution flaw, CVE-2026-50522 (CVSS 9.8), is being actively exploited against on-premises deployments after Microsoft released fixes for affected versions of SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Subscription Edition. The vulnerability stems from unsafe deserialization of untrusted data and can be triggered through unauthenticated requests, making internet-facing SharePoint farms particularly exposed. Researchers reported likely real-world exploitation against honeypots, and public proof-of-concept code is now available.
Reporting indicates attackers have targeted on-prem SharePoint instances and, in some cases, stolen machine keys to help preserve long-term access. The flaw was originally demonstrated during Pwn2Own Berlin, where exploit code was shown and shared with Microsoft before the vendor issued patches. Organizations running exposed SharePoint servers have been urged to apply the fixed versions immediately and, if patching cannot be completed at once, restrict external access and review logs for suspicious requests to SharePoint sign-in pages.
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4 events from the most recent confirmed update back to the earliest known activity.
Public exploit code for CVE-2026-50522 became available, increasing the risk to internet-facing SharePoint servers. Reports said the circulating proof of concept raised urgency for organizations to deploy Microsoft's patch quickly.
Researchers reported likely active exploitation of the SharePoint flaw against on-premises deployments and honeypots using unauthenticated requests. watchTowr said attackers were stealing machine keys to maintain long-term access.
During Pwn2Own Berlin in May, researchers demonstrated a working exploit for CVE-2026-50522 and provided the details to Microsoft. The flaw affects on-premises Microsoft SharePoint Server deployments and enables remote code execution via unsafe deserialization.
Microsoft released a patch for CVE-2026-50522 on 2026-07-14. The fix applies to affected on-premises SharePoint versions including Enterprise Server 2016, Server 2019, and Subscription Edition.
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Microsoft disclosed and patched **CVE-2026-58644**, a critical remote code execution flaw in **Microsoft SharePoint** caused by insecure deserialization of untrusted data (`CWE-502`). The vulnerability carries a **CVSS 9.8** rating and allows an **unauthorized attacker** to execute arbitrary code over the network by sending a crafted HTTP request, with **no user interaction required**. Affected products include **SharePoint Enterprise Server 2016**, **SharePoint Server 2019**, and **SharePoint Server Subscription Edition** prior to patched versions published through Microsoft's security guidance. Reporting on the release said no active exploitation had been confirmed at disclosure, but warned that exploitation is likely because SharePoint is widely deployed in enterprises; organizations were urged to prioritize patching internet-exposed SharePoint systems, review access permissions, and monitor server logs for suspicious activity.
Jul 17, 2026
More than **1,370 internet-facing Microsoft SharePoint servers** were reported exposed to active exploitation of **`CVE-2026-32201`**, a spoofing vulnerability affecting SharePoint Server 2016, 2019, and Subscription Edition. Microsoft disclosed the flaw in April and CISA added it to the **Known Exploited Vulnerabilities** catalog the same day, underscoring the urgency for defenders. Although Microsoft scored the bug at **CVSS 6.5**, the risk is elevated because it can be exploited **remotely without authentication** against exposed on-premises deployments, potentially allowing attackers to impersonate users, access or alter sensitive content, steal credentials, and move laterally inside victim environments. The exposure comes amid broader concern over SharePoint security, including Microsoft's disclosure of **`CVE-2026-26106`**, a **remote code execution** vulnerability in SharePoint Server, and earlier reporting that a **China-linked threat actor** was involved in SharePoint attacks, according to Mandiant. The concentration of exposed systems was highest in the **United States**, and the combined reporting points to sustained attacker interest in SharePoint as a route into enterprise networks. Organizations were urged to apply Microsoft's available updates, reduce direct internet exposure of SharePoint servers, and closely monitor authentication and document-access activity for signs of compromise.
Jun 29, 2026
CISA and Microsoft warned that multiple **on-premises SharePoint Server** vulnerabilities are being actively exploited against internet-facing systems, with attackers using a chain involving `CVE-2026-32201`, `CVE-2026-45659`, and `CVE-2026-56164` to gain unauthorized access, execute code, steal IIS and ASP.NET machine keys, maintain persistence, and deploy malware. The agencies said the activity affects supported on-premises SharePoint deployments rather than SharePoint Online, and follows earlier Microsoft reporting that Chinese threat actors including **Linen Typhoon**, **Violet Typhoon**, and **Storm-2603** had abused similar SharePoint flaws to install web shells, dump credentials, move laterally, and in some cases deploy **Warlock ransomware**. Microsoft’s July 2026 updates also fixed two additional critical SharePoint bugs, `CVE-2026-55040` and `CVE-2026-58644`, which were not yet confirmed as exploited but were assessed as likely targets for rapid weaponization, while separate reporting said another SharePoint exploit chain may remain unpatched pending a later release. Defenders were urged to immediately apply available patches, enable **AMSI** in Full Mode, reduce or remove internet exposure, restrict access to SharePoint Central Administration, review logs and endpoint telemetry for compromise, and only rotate IIS or ASP.NET machine keys after confirming whether intrusion activity is already present.
Jul 20, 2026