CVE-2026-62749 Overview
CVE-2026-62749 is a use-after-free vulnerability [CWE-416] in the Microsoft Windows Kernel. An authorized local attacker can exploit the flaw to elevate privileges on affected systems. Successful exploitation grants attackers execution in kernel context, allowing full control of the compromised host.
The vulnerability affects current Windows 11 branches and Windows Server 2025. Microsoft published the advisory on August 11, 2026. Exploitation requires local access and low privileges, but Microsoft rates attack complexity as high because the attacker must win a race window to trigger the freed object reuse.
Critical Impact
A local attacker with low privileges can execute code in kernel context, resulting in full compromise of confidentiality, integrity, and availability on the affected host.
Affected Products
- Microsoft Windows 11 24H2 (x64, ARM64)
- Microsoft Windows 11 25H2 (x64, ARM64)
- Microsoft Windows 11 26H1 (x64, ARM64)
- Microsoft Windows Server 2025
Discovery Timeline
- 2026-08-11 - Microsoft releases security advisory for CVE-2026-62749
- 2026-08-11 - CVE-2026-62749 published to NVD
- 2026-08-13 - Last updated in NVD database
Technical Details for CVE-2026-62749
Vulnerability Analysis
The flaw is a use-after-free condition [CWE-416] inside the Windows Kernel. The kernel references a memory object after it has been released, allowing an attacker who controls allocation timing to place attacker-influenced data at the freed address. When the kernel dereferences the stale pointer, the attacker gains control of execution flow in ring 0.
Exploitation requires local access and a low-privileged account. The attack complexity is high because the attacker must synchronize object freeing with a subsequent kernel access. Attackers commonly pair such flaws with heap spraying or pipe attribute manipulation to reliably reclaim the freed allocation.
Successful exploitation elevates the attacker from a standard user context to SYSTEM. Kernel-level code execution enables credential theft, security-tool tampering, and installation of persistent implants that survive reboots.
Root Cause
The root cause is improper lifetime management of a kernel object. The kernel releases the object while another code path retains a reference. Subsequent operations dereference the dangling pointer, treating attacker-controlled memory as a valid kernel structure.
Attack Vector
The attack vector is local. An attacker must already have code execution as a low-privileged user, typically obtained through phishing, a browser exploit, or a compromised service account. From that foothold, the attacker triggers the vulnerable kernel path to elevate to SYSTEM. Microsoft's advisory does not indicate active exploitation, and no public proof-of-concept is available. See the Microsoft CVE-2026-62749 Advisory for technical details.
Detection Methods for CVE-2026-62749
Indicators of Compromise
- Unexpected creation of processes running as NT AUTHORITY\SYSTEM from parent processes owned by standard users.
- Kernel bugcheck events referencing invalid pool addresses or dereferences immediately following user-mode activity from a non-privileged account.
- Loading of unsigned or unusual drivers shortly after a low-privileged process performs high-frequency kernel object allocation.
Detection Strategies
- Monitor for token manipulation and process access patterns consistent with local privilege escalation, including handle duplication from SYSTEM processes to user-owned processes.
- Correlate Windows Error Reporting WerFault crash reports and Event ID 1001 entries citing kernel-mode faults with recent user-initiated activity.
- Apply behavioral analytics to identify sudden privilege transitions on endpoints without corresponding administrative logon events.
Monitoring Recommendations
- Enable kernel-mode audit logging and forward Windows Security, System, and Sysmon event channels to a centralized analytics platform.
- Track driver load events (Event ID 6) and new service installations following any local process crash.
- Alert on abnormal spikes in named pipe, ALPC port, or handle table activity from unprivileged processes, which are common exploitation primitives for kernel use-after-free flaws.
How to Mitigate CVE-2026-62749
Immediate Actions Required
- Apply the Microsoft security update referenced in the Microsoft CVE-2026-62749 Advisory to all affected Windows 11 and Windows Server 2025 systems.
- Prioritize patching on multi-user systems, jump hosts, and terminal servers where low-privileged users have interactive access.
- Audit local account privileges and remove unnecessary interactive logon rights for standard users.
Patch Information
Microsoft has released security updates for Windows 11 24H2, 25H2, 26H1, and Windows Server 2025 on both x64 and ARM64 architectures. Refer to the Microsoft CVE-2026-62749 Advisory for the specific KB article and cumulative update applicable to each build.
Workarounds
- Microsoft has not published an official workaround; installing the security update is the only supported remediation.
- Restrict local logon rights and disable unnecessary local accounts to reduce the population of users able to trigger the flaw.
- Enforce application allowlisting to prevent unauthorized binaries from executing the exploitation primitive on the endpoint.
# Verify installed update on Windows using PowerShell
Get-HotFix | Sort-Object -Property InstalledOn -Descending | Select-Object -First 10
# Query current OS build to confirm patched version
[System.Environment]::OSVersion.Version
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
