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How CVE-2026-50413 Works
CVE-2026-50413 is a critical use‑after‑free (UAF) vulnerability residing in the Windows Runtime subsystem – the execution environment that enables modern Windows applications to run across the operating system. The flaw stems from improper memory management practices: when the runtime allocates memory for object references and later frees that memory, certain cleanup routines fail to properly invalidate dangling pointers or reset reference counts. As a result, subsequent legitimate operations within the Windows Runtime may still attempt to access memory blocks that have already been deallocated.
In a typical UAF scenario, the freed memory region can be repurposed by the attacker to contain malicious data or code. Because the original pointer still references that location, any later use of the pointer will operate on attacker‑controlled content rather than the intended runtime object. This behaviour is undefined and in practice leads to memory corruption, incorrect values, or – most critically – arbitrary code execution with the privileges of the calling process.
An authenticated attacker with a low‑privilege user account can trigger this vulnerability locally, without requiring network connectivity or complex external conditions. The attack surface is broad because Windows Runtime components are invoked across numerous application scenarios – from native UWP apps to various system services. By carefully crafting a sequence of operations that forces the runtime to free and then reuse a specific memory object, the attacker can hijack control flow and execute shellcode with elevated system privileges.
Successful exploitation effectively bypasses standard security boundaries such as user‑mode integrity levels and mandatory integrity controls. The flaw aligns with MITRE ATT&CK technique T1068 (Exploitation for Privilege Escalation) and is classified under CWE‑416 (Use After Free). Microsoft’s CVSS v3.1 vector string – `AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H` – yields a base score of 8.8 (High), reflecting the complete confidentiality, integrity, and availability impact on a compromised system. The vulnerability affects multiple Windows 11 versions (24H2, 25H2, 26H1) and Windows Server 2025, both full and Server Core installations.
DailyCVE Form:
Platform: Windows 11 / Server 2025
Version: 24H2,25H2,26H1,Server2025
Vulnerability: Use‑After‑Free (CWE‑416)
Severity: High (CVSS 8.8)
date: 2026‑07‑14
Prediction: Patch already released (July 2026)
What Undercode Say
Analytics & Telemetry
- EPSS – Not yet published (new CVE)
- CISA KEV – Not listed as actively exploited
- SSVC – Exploitation: none, Automatable: no, Technical Impact: total
- Patch Tuesday impact – July 2026 update contains fixes for 576 vulnerabilities; this is one of 255 Elevation of Privilege patches
Bash Commands to Check Affected Builds
Check Windows version and build number systeminfo | findstr /B /C:"OS Name" /C:"OS Version" Alternatively, using PowerShell Get-ComputerInfo | Select-Object WindowsVersion, WindowsBuildLabEx Check if the vulnerable runtime components are present Get-AppxPackage -Name "Runtime" | Select-Object -Property PackageFullName, Version
PowerShell – Verify Patch Status
List installed updates and filter for July 2026
Get-HotFix | Where-Object { $<em>.InstalledOn -ge [bash]"2026-07-01" } |
Format-Table HotFixID, Description, InstalledOn -AutoSize
Check for specific KB (replace with actual KB after advisory release)
Get-HotFix | Where-Object { $</em>.HotFixID -match "KB50" }
Exploit
A local, authenticated attacker can exploit this UAF by:
1. Identifying a Windows Runtime service that exposes a vulnerable object lifecycle (e.g., a COM or WinRT class with faulty reference counting).
2. Triggering the free – invoking a specific method or series of calls that causes the runtime to deallocate the target object while a valid reference still exists elsewhere.
3. Replacing the freed memory – using heap‑spray or other memory‑shaping techniques to occupy the freed region with attacker‑controlled data (e.g., a fake vtable or shellcode).
4. Re‑using the dangling pointer – forcing the runtime to call a method on the now‑controlled object, redirecting execution to the attacker’s payload with the privileges of the runtime process.
Because the vulnerability is local and requires only low‑privilege credentials, it is especially dangerous in enterprise environments where users have legitimate interactive logons. A successful exploit yields full SYSTEM or LOCAL SERVICE privileges, allowing the attacker to disable security products, exfiltrate sensitive data, or persist on the host.
Protection
- Apply the official Microsoft update – The fix is included in the July 2026 Patch Tuesday release. Refer to the Microsoft Security Update Guide for the specific KB .
- Enable Windows Defender Application Control (WDAC) – Restrict which binaries and scripts can execute, reducing the likelihood of arbitrary code execution even if memory corruption occurs.
- Deploy exploit protection – Use Windows Defender Exploit Guard (WDEG) with settings such as Force ASLR, Validate Heap, and Validate Image Dependency Integrity to make UAF exploitation more difficult.
- Monitor Windows Runtime activity – Enable advanced audit logging for process creation and privilege escalation events (Event ID 4672, 4688, 4704) to detect anomalous behaviour.
- Reduce user privileges – Follow the principle of least privilege; limit administrative accounts and use just‑in‑time (JIT) elevation tools.
- Implement automated patch management – Ensure that critical security updates are deployed within the recommended SLA to minimise exposure windows.
Impact
- Complete system compromise – An attacker who successfully exploits this vulnerability gains full administrative control over the affected machine.
- Bypass of security boundaries – The flaw undermines user‑mode integrity and mandatory integrity controls, allowing the attacker to operate with SYSTEM privileges.
- Lateral movement – Once elevated on one host, the attacker can use stolen credentials or tokens to move laterally across the network.
- Data breach – With high privileges, sensitive files, registry hives, and memory‑resident secrets (e.g., LSASS credentials) become accessible.
- Persistence – The attacker can install rootkits, scheduled tasks, or services that survive reboots, maintaining long‑term access.
- Business disruption – Exploitation may lead to service outages, especially if the runtime component is critical for system stability or line‑of‑business applications.
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Sources:
Reported By: nvd.nist.gov
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