Patch tracker / CVE reference / CVE-2026-55040
CVE-2026-55040
Updated July 22, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
In the top 10 of the Senserva CVE Ranking (as of 2026-07-22)Critical severity Microsoft vulnerability, CVSS 9.1.
All about CVE-2026-55040: the Senserva AI read, whether it is exploited, how to fix it, what the press says about it, its change history, and the questions admins ask.
A Security Feature Bypass vulnerability affecting Microsoft SharePoint Enterprise Server 2016.
Risk summary
Senserva provides Three Free Unlimited Audits, including all tenants and full Claude MCP.Start my Audit
Senserva AI Opinion for CVE-2026-55040
CVE-2026-55040 is a Security Feature Bypass in Microsoft SharePoint Server rated Critical at CVSS 9.1. It applies to Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019, and Microsoft SharePoint Server Subscription Edition, so shops running any of those three on-premises builds are in scope; SharePoint Online is not listed. A Security Feature Bypass means an attacker circumvents a protection that SharePoint relies on rather than directly running code, which for a 9.1 score points to a defense being defeated with low complexity and no or minimal privilege, widening what a follow-on attack can reach. As of these facts, CISA has not confirmed active exploitation and there is no known ransomware use, so this is a patch-before-it-turns hot situation rather than an in-progress incident. Because SharePoint farms hold document libraries, permissions, and service accounts wired into Active Directory, a bypass on these specific versions can matter more than the raw label suggests for identity and content exposure.
Do this: Inventory every on-premises farm to confirm whether it is SharePoint Enterprise Server 2016, Server 2019, or Subscription Edition, since only these three are named as affected. Apply the Microsoft security update issued for CVE-2026-55040 to each affected server in the farm and complete any post-install steps SharePoint requires, then confirm the build number reflects the patched version. Until patching is finished, restrict and monitor external access to SharePoint web front ends and review recent authentication and permission-change logs for anomalies given the bypass nature of this flaw. Re-check CISA KEV and the Microsoft advisory after patching in case exploitation status changes from the current no.
AI-generated from public data, 2026-07-22. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2026-55040
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for CVE-2026-55040
Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.
What the press says about CVE-2026-55040
Trusted-source coverage, pulled live from their own feeds.
How to fix CVE-2026-55040
Apply the latest Microsoft security update for the affected product. Most environments deliver it automatically through Intune update rings, Windows Update for Business, Windows Autopatch, or WSUS; for a manual install, download from the Microsoft Update Catalog. The MSRC advisory lists the exact patched build per product.
Affected products
Common questions about CVE-2026-55040
Is CVE-2026-55040 actively exploited?
It is not currently listed in the CISA Known Exploited Vulnerabilities catalog. That can change: unexploited CVEs regularly get weaponized months after disclosure, which is why patching on your normal cadence matters.
What fixes CVE-2026-55040?
Microsoft ships the fix in its security updates. Apply the latest cumulative or security update for the affected product through Windows Update, Intune, Windows Update for Business, or the Microsoft Update Catalog, and see the MSRC advisory below for the exact build.
Which products are affected by CVE-2026-55040?
Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019, Microsoft SharePoint Server Subscription Edition.
Can I ask my own AI about CVE-2026-55040?
Yes. This page includes a free, ready-to-paste AI prompt with CVE-2026-55040's key facts: severity, CVSS, CISA KEV status, and the affected products. Copy it into Claude, ChatGPT, or Copilot for a triage plan.
Authoritative references
Every Microsoft CVE and the patches that fix it, ranked by real-world risk: the Microsoft Patch Tracker. The full searchable CVE reference: CVE and vulnerability management.
