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Introduction: A Massive Security Update That Changes How Organizations Must Prioritize Risk
Microsoft has delivered what is being described as its largest Patch Tuesday release ever, closing 622 vulnerabilities across its ecosystem in a single update cycle. While the sheer number of fixes is enough to attract attention, the most important details are hidden among the numbers: two vulnerabilities are already being exploited by attackers in real-world campaigns.
The affected technologies are not ordinary endpoints. They sit at the center of enterprise operations: SharePoint Server, which stores sensitive business documents, and Active Directory Federation Services (AD FS), which controls identity trust across organizations.
This release highlights a growing challenge in modern cybersecurity. Attackers are no longer relying only on highly rated remote code execution flaws. Instead, they are increasingly targeting identity systems and privilege escalation weaknesses because gaining trust inside an organization can be more valuable than simply breaking into a machine.
Microsoft’s July security update serves as another reminder that vulnerability management cannot depend only on severity scores. Organizations must focus on what attackers are actively exploiting, what systems control critical access, and which vulnerabilities can become stepping stones for larger attacks.
Microsoft’s Largest Patch Tuesday Ever: 622 Vulnerabilities Fixed
A Record Number of Security Fixes Arrive in One Month
Microsoft’s latest Patch Tuesday release includes 622 unique CVEs, making it the largest security update published by the company to date. The figure represents a dramatic increase compared with previous months, where vulnerability counts were significantly lower.
Windows systems account for the majority of the fixes, with 416 vulnerabilities addressed, followed by Office products, Edge, SharePoint Server, developer tools, Azure services, SQL Server, Defender, and Exchange Server.
The size of the update reflects both the growing complexity of Microsoft’s ecosystem and the increasing use of automated security discovery tools capable of identifying large numbers of flaws.
Two Zero-Day Vulnerabilities Are Already Being Exploited
SharePoint Server Flaw Allows Remote Privilege Escalation
The most urgent vulnerability in this release is CVE-2026-56164, a SharePoint Server security flaw that Microsoft confirms is being exploited in active attacks.
The vulnerability allows an unauthenticated attacker to escalate privileges remotely through the network. No valid account credentials and no user interaction are required, making it especially dangerous for organizations running self-hosted SharePoint environments.
Microsoft credited researchers from Mandiant incident responders and Google’s FLARE team for identifying the vulnerability, suggesting that the discovery may have come from investigations into ongoing attacks.
Although Microsoft has not publicly revealed who is exploiting the flaw or the exact attack methods being used, the combination of remote access, no authentication requirements, and SharePoint’s role in enterprise environments makes this vulnerability a high-value target.
SharePoint Remains a Major Target for Attackers
A History of Abuse Makes This Patch More Urgent
SharePoint has become one of the most frequently targeted enterprise platforms in recent years. Attackers understand that compromising SharePoint can provide access to sensitive documents, internal collaboration data, and potentially a path toward broader network compromise.
Previous SharePoint attack chains demonstrated how quickly unpatched servers can become entry points for ransomware groups, espionage campaigns, and financially motivated attackers.
Organizations running SharePoint Server should treat CVE-2026-56164 as a priority remediation item and apply Microsoft’s recommended protections immediately.
Microsoft also recommends enabling AMSI Full Mode on SharePoint servers, which can help detect and block malicious activity targeting the platform.
Active Directory Federation Services Vulnerability Threatens Identity Infrastructure
CVE-2026-56155 Targets the Heart of Enterprise Authentication
The second actively exploited vulnerability is CVE-2026-56155, affecting Active Directory Federation Services.
Unlike the SharePoint issue, this vulnerability requires an attacker to already have authentication on the local system. However, its impact may be far more significant because AD FS is responsible for issuing authentication tokens that other services trust.
A compromise of AD FS can become a gateway to identity abuse, allowing attackers to impersonate users, access cloud services, and move deeper into enterprise environments.
Microsoft’s Detection and Response Team (DART) discovered the issue, but details about exploitation methods and attacker activity remain limited.
Why “Local” Identity Vulnerabilities Can Become Enterprise Disasters
Privilege Labels Do Not Always Represent Real-World Risk
Security teams often prioritize vulnerabilities based on severity ratings and whether they are remotely exploitable. However, identity infrastructure changes the equation.
A vulnerability classified as “local privilege escalation” on an authentication server may provide attackers with access that is far more valuable than a remote flaw affecting a normal workstation.
AD FS, domain controllers, certificate systems, and identity providers are among the most sensitive assets in modern networks. A small privilege increase in these environments can create a major security incident.
CISA KEV Listing Is Not Required Before Taking Action
Exploitation Evidence Already Exists
At the time of publication, neither CVE-2026-56164 nor CVE-2026-56155 appears in the CISA Known Exploited Vulnerabilities catalog.
However, organizations should not wait for a KEV listing before responding.
Microsoft has already confirmed exploitation, meaning defenders should consider these vulnerabilities active threats regardless of external catalog updates.
The growing speed of cyberattacks means waiting for additional confirmation can provide attackers with valuable time.
A Third Vulnerability: BitLocker Bypass Disclosed
CVE-2026-50661 Requires Physical Access
Microsoft also patched a publicly disclosed BitLocker bypass vulnerability, tracked as CVE-2026-50661.
Unlike the two exploited vulnerabilities, this issue requires physical access to a device, reducing its immediate threat level for most organizations.
While important to patch, it does not require the same emergency response as the SharePoint and AD FS vulnerabilities.
The flaw continues a series of BitLocker-related security issues discovered throughout the year, showing continued attention toward encryption protection mechanisms.
Rapid7 Reveals Another SharePoint Authentication Bypass
CVE-2026-55040 Creates a Dangerous Attack Chain
Another major SharePoint issue was disclosed by Rapid7 Labs as part of its Pwn2Own Berlin research.
Tracked as CVE-2026-55040, the vulnerability involves a JWT authentication bypass affecting SharePoint Server.
The severity rating has caused debate among researchers. Rapid7 assigned a medium severity score, while Zero Day Initiative (ZDI) classified it as critical.
The disagreement comes from how the vulnerability can be combined with another remote code execution flaw. Together, the weaknesses create a potential path to unauthenticated remote code execution.
Microsoft plans to release a fix for the related RCE component in August, meaning July’s update acts as a temporary barrier that breaks the attack chain.
Microsoft Removes the RC4 Rollback Safety Net
Legacy Kerberos Encryption Could Break After Updating
This Patch Tuesday also completes Microsoft’s long-running effort to eliminate RC4 encryption from Kerberos authentication.
The update removes the RC4DefaultDisablementPhase rollback option, meaning organizations will no longer have the same ability to restore older RC4 behavior.
After the change, RC4 authentication will only continue for accounts specifically configured to allow it.
Organizations that still depend on older service accounts or legacy applications may experience authentication failures after deployment.
Administrators Must Audit Before Applying the Change
Preparation Is Critical to Avoid Outages
Microsoft recommends organizations first review RC4 audit events introduced earlier in the year.
The correct process involves:
Identifying accounts still requesting RC4 Kerberos tickets.
Rotating passwords for affected service accounts.
Ensuring AES encryption keys are generated.
Updating legacy applications that cannot support modern authentication.
This change is unlikely to cause security breaches directly, but poor preparation could result in unexpected service disruptions.
Windows Receives Hundreds of Security Fixes
The Largest Share of Vulnerabilities Comes From Microsoft’s Core Platform
Windows alone accounts for 416 vulnerabilities in this release.
Among the notable Windows fixes are:
CVE-2026-56155 affecting AD FS.
CVE-2026-50661 affecting BitLocker.
CVE-2026-57092, a Virtual Machine Switch vulnerability rated 9.9.
Multiple DHCP remote code execution vulnerabilities.
Numerous NTFS and ReFS driver security issues.
The scale demonstrates how difficult maintaining a modern operating system has become.
Office, Edge, SharePoint, and Enterprise Products Also Receive Major Fixes
Microsoft’s Ecosystem Faces Broad Security Pressure
Office products received 82 fixes, while Microsoft Edge received 46 security patches.
SharePoint Server received 17 fixes, including the exploited zero-day and additional authentication-related issues.
Developer tools received 27 fixes, including security feature bypasses affecting Visual Studio, VS Code, and GitHub Copilot-related components.
SQL Server, Defender, Exchange Server, and Azure services also received important security updates.
Microsoft’s AI Security Research Pipeline Is Changing Vulnerability Discovery
Automation Is Finding More Bugs Faster
Microsoft revealed that artificial intelligence-assisted security research is contributing to its vulnerability discovery process.
The company previously announced its multi-model agentic scanning system, known as MDASH, which discovered multiple vulnerabilities in earlier security releases.
While Microsoft has not disclosed how many July vulnerabilities were found through AI-assisted research, the company expects automated discovery to increase the volume of future security updates.
The New Security Reality: Patch Speed Matters More Than Ever
Attackers Can Reverse Engineer Fixes Quickly
Once Microsoft releases patches, attackers can analyze the changes and identify what vulnerabilities were fixed.
This creates a race between defenders applying updates and attackers developing exploits.
The traditional approach of waiting days or weeks before patching is becoming increasingly dangerous, especially for internet-facing systems.
Why CVSS Scores Are Losing Their Importance
Exploitation Matters More Than Numbers
The biggest lesson from this Patch Tuesday is that severity scores alone are no longer enough.
The two most urgent vulnerabilities were not necessarily the highest-rated issues in the release. Instead, they were dangerous because attackers were already using them.
Security teams should prioritize:
Confirmed exploitation.
CISA KEV listings.
Microsoft exploitation indicators.
Exposure of affected systems.
Business importance of affected assets.
A vulnerability’s true danger depends on context, not only its numerical score.
What Undercode Say: Deep Analysis
Identity Systems Are Becoming the Main Battlefield
The latest Microsoft update shows a clear shift in cyberattack strategies. Attackers increasingly understand that controlling identity infrastructure provides more long-term value than simply deploying malware.
A compromised SharePoint server can expose confidential information, but a compromised authentication system can unlock an entire organization.
SharePoint Continues to Be a Strategic Target
The repeated targeting of SharePoint demonstrates that attackers view collaboration platforms as valuable entry points.
Organizations often protect endpoints aggressively while overlooking internal business applications that contain sensitive information.
SharePoint servers exposed without rapid patching can become attractive targets for ransomware operators and espionage groups.
Privilege Escalation Is Becoming More Dangerous
Traditional security thinking often treats privilege escalation bugs as secondary compared with remote code execution vulnerabilities.
That approach is becoming outdated.
Attackers frequently combine smaller vulnerabilities to create powerful attack chains.
A medium-severity privilege flaw on a critical identity server can be more valuable than a critical vulnerability on a less important system.
Patch Management Must Become Intelligence Driven
Organizations cannot realistically treat hundreds of vulnerabilities equally.
Modern patching requires intelligence-based prioritization.
Security teams need to know:
Which vulnerabilities are exploited.
Which systems are exposed.
Which assets control identity.
Which weaknesses can be chained together.
AI Will Accelerate Both Defense and Attack
Microsoft’s use of AI-driven vulnerability discovery represents a major change in cybersecurity.
Defenders will discover flaws faster, but attackers will also analyze patches faster.
The window between vulnerability disclosure and exploitation will continue shrinking.
Legacy Technology Remains a Hidden Security Risk
The RC4 phase-out highlights another long-standing issue: outdated technology creates security problems.
Many organizations still depend on old applications, authentication methods, and service accounts.
Security improvements often fail because businesses delay modernization.
The Future of Cybersecurity Requires Faster Decisions
The era of slow vulnerability management is ending.
Organizations must move toward continuous assessment, automated monitoring, and rapid remediation.
Attackers are already operating at machine speed, and defenders must adapt.
✅ Confirmed: Microsoft released a record-sized Patch Tuesday update containing hundreds of security fixes, including vulnerabilities affecting major enterprise products.
✅ Confirmed: Microsoft identified CVE-2026-56164 and CVE-2026-56155 as vulnerabilities exploited in active attacks.
❌ Not Confirmed: Microsoft has not publicly identified the attackers behind the exploitation campaigns or provided complete technical details about attack methods.
Prediction
(+1) Positive Outlook
Organizations that quickly prioritize exploited vulnerabilities, improve identity protection, and remove legacy authentication methods will significantly reduce their exposure to future attacks.
(-1) Negative Outlook
Attackers are likely to continue targeting identity platforms such as SharePoint, AD FS, and authentication systems because these weaknesses provide high-value access to enterprise networks.
(-1) Negative Outlook
As Microsoft and other vendors release larger security updates, organizations that rely on manual patching processes will struggle to keep pace with increasingly rapid exploitation cycles.
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