Full Report
Microsoft has released its monthly security update for July 2026, which includes 622 vulnerabilities affecting a range of products, including 57 that Microsoft marked as "critical".Microsoft notes that two of the vulnerabilities disclosed this month have been exploited in the wild.CVE-2026-56155 is an important-
Analysis Summary
# Vulnerability: Microsoft July 2026 Patch Tuesday Monthly Update
## CVE Details
- **CVE ID:** CVE-2026-56155, CVE-2026-56164 (and 620 others)
- **CVSS Score:** Varies (Up to 9.8/10.0 for Critical RCEs)
- **Severity:** 57 Critical, 565 Important/Moderate
- **CWE:** CWE-284 (Improper Access Control), CWE-287 (Improper Authentication), CWE-122 (Heap-based Buffer Overflow), CWE-416 (Use-After-Free), CWE-502 (Deserialization of Untrusted Data), CWE-362 (Race Condition).
## Affected Systems
- **Identity & Auth:** Active Directory Federation Services (AD FS), AD Domain Services.
- **Server Infrastructure:** Windows DHCP Server, SharePoint Server, SQL Server, MSMQ, Windows Server Network Driver.
- **Productivity:** Microsoft Office (Word, Excel, PowerPoint), Dynamics 365 Business Central/NAV.
- **Operating System:** Windows TCP/IP, Print Spooler, GDI/GDI+, DirectX Graphics Kernel, Win32k, Boot Loader, SMB.
- **Multimedia:** Windows Media, Media Foundation.
- **Other:** Minecraft Bedrock Dedicated Server, Microsoft Copilot, Microsoft Defender.
## Vulnerability Description
This massive update addresses various flaw types:
- **Authorization/Authentication:** AD FS suffers from insufficient access control granularity (CVE-2026-56155), while SharePoint lacks authentication for critical functions (CVE-2026-56164).
- **Memory Corruption:** Multiple heap-based buffer overflows and use-after-free flaws in DHCP services and Windows Media components allow for arbitrary code execution.
- **Deserialization:** SharePoint and Dynamics NAV/365 fail to safely deserialize data, allowing remote code execution (RCE).
- **Logic Flaws:** A race condition exists within the Windows Server Network Driver (CVE-2026-56188).
## Exploitation
- **Status:** **Exploited in the Wild** (CVE-2026-56155 and CVE-2026-56164). Several others are marked "More Likely" to be exploited.
- **Complexity:** Ranges from Low to High.
- **Attack Vector:** Primarily **Network** (Remote) and **Adjacent** (Network/Local). 48 critical vulnerabilities enable RCE.
## Impact
- **Confidentiality:** High (Data theft via RCE/Spoofing)
- **Integrity:** High (Unauthorized system modification/Privilege Elevation)
- **Availability:** High (System crashes via memory corruption)
## Remediation
### Patches
Microsoft has released official updates. Administrators should apply the July 2026 cumulative updates for their specific OS versions and software:
- Windows 10/11 and Windows Server 2019/2022/2025.
- Microsoft 365 Apps, Office 2021/2024.
- SharePoint Server 2019/Subscription Edition.
- Dynamics 365 Business Central (On-premises).
### Workarounds
- **AD FS:** Ensure strict local access policies to mitigate local elevation of privilege.
- **MSMQ:** Disable the Message Queuing service if not required by business applications.
- **Print Spooler:** Stop and disable the Print Spooler service on domain controllers and non-printing servers.
## Detection
- **Indicators of Compromise:** Monitor for unusual elevation of privileges in AD FS logs or unauthorized spoofing attempts in SharePoint traffic.
- **Detection Tools:**
- **Snort 2 Rules:** 1:66733 - 1:66743, 1:66745 - 1:66785, 1:66791 - 1:66793, 1:66800 - 1:66807.
- **Snort 3 Rules:** 1:301555 - 1:301579, 1:301581 - 1:301583.
- **Cisco Firepower:** Update SRU to include the July 2026 rule set.
## References
- Microsoft Security Update Guide (July 2026): hxxps[://]msrc[.]microsoft[.]com/update-guide/releaseNote/2026-Jul
- Cisco Talos Blog: hxxps[://]blog[.]talosintelligence[.]com/
- Snort Rules: hxxps[://]www[.]snort[.]org/