Microsoft ships fixes for 570 flaws in July, including two bugs already used in attacks
The July 2026 Patch Tuesday is the largest on record, driven partly by an AI system Microsoft is using to hunt bugs in Windows.
Key points
- Microsoft released fixes for 570 security flaws on 14 July 2026, its largest ever monthly patch batch.
- Two of the flaws were already being used in real attacks: one in Active Directory Federation Services and one in SharePoint Server.
- A third flaw, a BitLocker bypass that lets someone with physical access read encrypted data, was publicly disclosed before the patch shipped.
- 59 of the 570 flaws are rated Critical, including 48 that allow remote code execution (attackers running their own code on a target machine).
- Microsoft says an AI-powered bug-finding system is one reason the numbers keep climbing.
Microsoft's July 2026 Patch Tuesday addresses 570 vulnerabilities, the largest single-month total the company has ever released. Three are zero-days, meaning flaws that were exploited or publicly known before a patch existed. Two were already in active use by attackers.
The count excludes 468 Chromium flaws Google fixed this month that carry over into Microsoft Edge, plus cloud-service fixes Microsoft shipped earlier in July, per BleepingComputer's methodology.
What are the flaws attackers are already using?
The first is CVE-2026-56155, an elevation-of-privilege bug in Active Directory Federation Services (AD FS), the Microsoft component that handles single sign-on, letting staff access many company apps with one login. It allows an attacker who already has a foothold on the server to promote themselves to administrator. Microsoft credited Jeremy Kingston and Scott Clark of its Detection and Response Team (DART), the company's incident response unit, which typically means the bug surfaced during investigation of a live intrusion. No details on the targets have been released.
The second is a SharePoint Server flaw letting a remote attacker gain higher privileges without any login at all. Microsoft describes it as "missing authentication for critical function," meaning SharePoint was letting outsiders call an internal function that should have required a password. Administrators who can't patch immediately can enable the Antimalware Scan Interface (AMSI) with Request Body Scan set to Full as a temporary measure. The flaw was credited to Jayson Frost of Mandiant Incident Response, Genwei Jiang of Google Cloud's FLARE OTF team, and an anonymous researcher. We flagged a separate actively exploited SharePoint deserialization bug on 2 July, so this is now the second SharePoint zero-day in a fortnight that defenders need to account for.
The third zero-day is a BitLocker bypass. BitLocker encrypts a laptop's hard drive so a thief can't read the files; this flaw lets an attacker with physical access defeat that protection. It was publicly disclosed before a patch was ready, though Microsoft says it hasn't seen it used in attacks.
Why are the numbers so big this month?
Last week Microsoft warned that Patch Tuesdays would get heavier because it's started using an AI-powered vulnerability discovery system to comb the Windows source code for bugs before criminals find them. The side effect is a surge of new CVEs (the standard tracking IDs for security flaws) in a single month.
Of the 570 fixes, 59 are rated Critical. Inside that bucket: 48 are remote code execution flaws, 9 are elevation of privilege, 1 is a security feature bypass, and 1 is a spoofing bug.
Notable Critical fixes include CVE-2026-49164 in Active Directory Domain Services, which controls Windows logins across an entire organisation, and CVE-2026-54121 in Active Directory Certificate Services.
Should you worry?
Prioritise the AD FS and SharePoint patches. Both are under active exploitation, both sit at the identity layer, and that's exactly where attackers want to plant a flag. If SharePoint can't be patched today, apply the AMSI mitigation now and treat it as a stopgap, not a fix.
Home users don't need to act manually. Windows Update handles this. If your machine asks for a restart this week, don't defer it.
The AI-driven patch volume is worth watching: bigger batches mean more chances for something important to get buried. The DART attribution on the AD FS bug is the detail that should concern enterprise teams most. That team doesn't credit itself unless it found the flaw in someone else's network.
