CVE-2026-49795

What it actually does

CVE-2026-49795 is a local privilege escalation vulnerability caused by a use-after-free condition in the Windows Kernel. A low-privileged, authenticated local attacker can trigger incorrect kernel memory object lifetime handling and potentially execute code in kernel context. Successful exploitation can allow the attacker to elevate privileges from a standard user context to highly privileged local authority, compromising confidentiality, integrity, and availability of the affected Windows system. The CVSS vector indicates local access is required, attack complexity is low, no user interaction is needed, and scope changes because exploitation crosses from a lower-privileged user context into kernel-level control.

Why it matters to the business

If exploited, this flaw can let an attacker who already has a foothold on a Windows workstation or server take full control of that machine. In business terms, it increases the impact of phishing, stolen credentials, malware execution, or compromise of a low-privileged account because the attacker can potentially disable security tooling, dump credentials, tamper with data, move laterally, or deploy additional payloads. Affected platforms include multiple Windows 10, Windows 11, and Windows Server releases, so exposure may be broad across enterprise endpoints and servers. It is not currently listed in CISA KEV, is not marked as ransomware-associated, and has low EPSS at the time provided, but the high CVSS score and local privilege escalation value make it important to remediate through normal or accelerated patch cycles, especially on shared systems, administrative workstations, domain-joined endpoints, and internet-facing servers where attackers may first gain low-privileged code execution through another weakness.

How an attack unfolds

An attacker must first obtain the ability to run code locally on an affected Windows system, such as through malware execution, abuse of a low-privileged account, exploitation of an application flaw, or interactive access. The attacker then runs a purpose-built exploit that triggers the Windows Kernel use-after-free condition. By manipulating memory allocation and object reuse, the exploit attempts to cause freed kernel memory to be reused in a controlled way, allowing the attacker to alter kernel execution flow or security-relevant kernel data. If successful, the attacker obtains elevated local privileges, commonly equivalent to SYSTEM or another highly privileged context. From there, the attacker can disable defenses, access sensitive files, dump credentials, install persistence, create privileged accounts, tamper with logs, or use the compromised host as a staging point for lateral movement. No public exploit maturity was provided, and the vulnerability is not currently identified as KEV, but local privilege escalation bugs in the Windows Kernel are frequently chained after initial access.

How to fix it

Apply the Microsoft security update that addresses CVE-2026-49795 for all affected Windows versions, including Windows 10 1809, 21H2, and 22H2; Windows 11 24H2, 25H2, and 26H1; Windows Server 2019; Windows Server 2022; and Windows Server 2025. Because no exact fixed build numbers were provided, use Microsoft Security Update Guide, Windows Update, WSUS, Microsoft Configuration Manager, Intune, or the Microsoft Update Catalog to identify and deploy the applicable cumulative update released on or after the publication date. Prioritize systems where local privilege escalation would materially increase risk, including servers, privileged access workstations, developer workstations, VDI hosts, jump boxes, and endpoints used by administrators. If immediate patching is not possible, reduce exposure by removing unnecessary local accounts, enforcing least privilege, blocking untrusted code execution, enabling endpoint protection and attack surface reduction rules, restricting interactive logon to servers, and monitoring for abnormal privilege escalation behavior. There is no reliable configuration-only mitigation for a kernel use-after-free vulnerability; patching is the primary remediation.

How to confirm the fix worked

Confirm remediation by verifying that each affected Windows system has installed the applicable Microsoft cumulative security update that supersedes the vulnerable kernel components. Use enterprise patch reporting, vulnerability scanners, Microsoft Defender Vulnerability Management, WSUS/Configuration Manager/Intune compliance data, or local commands such as `winver`, `systeminfo`, and `Get-HotFix` to confirm the OS build and installed KB level match Microsoft guidance for the fixed release. Validate a representative sample of endpoints and servers after deployment, including reboot status, because Windows kernel fixes typically require a restart to take effect. Confirm vulnerability scanners no longer report the CVE on patched systems. For systems that cannot be patched, document the exception, compensating controls, owner, and target remediation date.

Typical attack path

1. Gain initial local code execution on an affected Windows workstation or server using phishing, malware, stolen credentials, remote application compromise, or interactive access.
2. Confirm the target is running an affected Windows version and lacks the relevant Microsoft security update.
3. Execute a local exploit designed to trigger the Windows Kernel use-after-free condition.
4. Manipulate kernel memory state so the freed object is reused in a way that grants elevated execution or alters security controls.
5. Spawn or inject into a high-privileged process, commonly SYSTEM-level context.
6. Disable or evade endpoint protections, collect credentials, access protected data, or establish persistence.
7. Use the elevated host access to move laterally, escalate domain privileges, or deploy additional payloads.

How to detect it

There are no universally reliable, vulnerability-specific indicators for this Windows Kernel use-after-free flaw from the provided information. To assess possible prior exploitation, focus on behavioral evidence of local privilege escalation and post-exploitation activity. Review Windows Security logs, Sysmon logs, Microsoft Defender for Endpoint telemetry, EDR process trees, PowerShell logs, application control logs, and system event logs from affected hosts, especially where low-privileged user activity is followed by SYSTEM-level process execution. Look for abnormal parent-child process relationships, unexpected services or scheduled tasks created shortly after user logon, suspicious process injection, unsigned or unusual driver loads, credential dumping attempts, endpoint protection tampering, new local administrators, and audit policy changes. Relevant Windows events include process creation if enabled, service creation, scheduled task registration, local group membership changes, special privilege assignment, log clearing, and Defender tampering alerts. Correlate suspicious events with systems that were unpatched at the time. Since no named threat actors, ransomware usage, public exploit artifacts, filenames, hashes, or network signatures were provided, detection should rely on endpoint behavior rather than static IOCs.

What your security team should do

• Prioritize deployment of the applicable Microsoft cumulative security updates across affected Windows workstation and server versions.
• Patch or isolate high-value systems first, including domain controllers if affected by OS version, administrative workstations, jump servers, VDI infrastructure, and internet-facing Windows servers.
• Use centralized patch management to verify both installation and post-patch reboot completion.
• Hunt for signs of local privilege escalation on systems that had prior suspicious activity, malware alerts, or untrusted local code execution before patching.
• Restrict local administrator membership and remove stale or unnecessary privileged accounts to reduce post-exploitation impact.
• Enforce application control, attack surface reduction rules, credential protection, and tamper protection to make local exploit execution and follow-on activity harder.
• Monitor for unusual SYSTEM-level process creation, suspicious driver loading, security tool tampering, credential dumping behavior, and unexpected privilege assignment events.
• Treat this vulnerability as a likely chaining target even though it is not currently in KEV and no public exploit maturity was provided.