CVE-2026-54115

What it actually does

This vulnerability is a local privilege escalation flaw in Windows Active Directory caused by an integer overflow or wraparound condition. An attacker who already has a valid low-privileged account or local execution context on an affected Windows system can trigger vulnerable Active Directory-related code paths to corrupt logic, memory, or authorization handling in a way that elevates their privileges. Successful exploitation can result in high-impact compromise of confidentiality, integrity, and availability on the affected host, potentially allowing the attacker to run code or perform actions with elevated local privileges.

Why it matters to the business

An attacker who has already gained limited access to a Windows workstation or server could use this flaw to become highly privileged on that system, increasing the likelihood of credential theft, persistence, security tool tampering, lateral movement, and domain-impacting activity if the affected host is a server or administrative workstation. Because the affected product range includes many supported Windows client and server versions, organizations with broad Windows deployments should treat this as an important patching priority even though it is not currently listed in CISA KEV and no public exploit maturity is reported.

How an attack unfolds

Exploitation requires the attacker to already be authenticated or have local code execution as a low-privileged user on an affected Windows system. The attacker would run a specially crafted local program or invoke a vulnerable Active Directory-related interface in a way that causes an integer value to overflow or wrap around. That arithmetic error can cause the operating system or service to make incorrect size, bounds, or privilege decisions, allowing the attacker to cross a local security boundary. If successful, the attacker obtains elevated privileges on the host and can then dump credentials, disable defenses, install persistence, access protected data, or use the compromised system as a staging point for further movement. There are no named threat actors or confirmed active exploitation associated with the provided data, but this class of vulnerability is commonly valuable after initial access because it turns a foothold into administrative control.

How to fix it

Apply the relevant Microsoft security updates for all affected Windows versions as soon as they are available through Windows Update, Microsoft Update Catalog, WSUS, Microsoft Configuration Manager, or equivalent patch management tooling. Affected products include Windows 10 1607, 1809, 21H2, and 22H2; Windows 11 24H2, 25H2, and 26H1; and Windows Server 2012, 2016, 2019, 2022, and 2025. No exact fixed build numbers were provided in the input, so remediation should be validated against Microsoft’s official security update guidance for the July 2026 release or later cumulative updates. Where immediate patching is not possible, reduce exposure by limiting interactive logon rights, restricting local administrator pathways, enforcing least privilege, monitoring privileged group membership changes, preventing untrusted local code execution with application control, and ensuring endpoint detection and response protections are active and tamper-protected.

How to confirm the fix worked

Confirm that each affected system has installed the Microsoft cumulative update or security update that supersedes the vulnerable release. Validate through centralized patch management inventory, Windows Update history, Microsoft Defender Vulnerability Management, Configuration Manager compliance baselines, or PowerShell checks such as querying installed hotfixes and OS build numbers. Because no fixed versions were supplied, compare installed builds and KBs against Microsoft’s official advisory for this vulnerability. Also validate that low-privileged users cannot write to privileged directories, modify services, create scheduled tasks with elevated rights, or obtain administrative tokens through local testing in a controlled environment. For exposure reduction, review which users retain local logon access and local administrative rights on Windows clients and servers.

Typical attack path

1. Obtain valid low-privileged credentials or local code execution on an affected Windows client or server.
2. Confirm the host is running a vulnerable Windows version and has the relevant Active Directory components or code paths available.
3. Execute a crafted local exploit or tool that triggers the integer overflow or wraparound condition.
4. Cause the vulnerable code to mishandle bounds, sizes, or authorization state.
5. Gain elevated local privileges on the affected system.
6. Use the new privileges to access sensitive files, dump credentials, modify security settings, install persistence, or move laterally.

How to detect it

Look for evidence of local privilege escalation followed by post-exploitation activity rather than a single definitive exploit signature, because no public exploit indicators were provided. Relevant log sources include Windows Security logs, System logs, PowerShell logs, Sysmon or EDR telemetry, Microsoft Defender alerts, service control manager events, scheduled task logs, and identity logs for privileged group changes. Review activity from low-privileged accounts that suddenly perform administrative actions, especially shortly before credential dumping, service creation, security control tampering, or lateral movement. Key Windows events to review include successful logons, privilege assignment, privileged group membership changes, process creation, service installation, scheduled task creation, explicit credential use, and security log clearing. Focus investigations on affected Windows versions and on systems where a non-admin account becomes associated with administrative tokens, new services, new scheduled tasks, LSASS access, or unexpected changes to local administrators.

• Event ID 4672 - Special privileges assigned to new logon
• Event ID 4688 - New process created
• Event ID 4720 - A user account was created
• Event ID 4728 - A member was added to a security-enabled global group
• Event ID 4732 - A member was added to a security-enabled local group
• Event ID 4756 - A member was added to a security-enabled universal group
• Event ID 4624 - An account was successfully logged on
• Event ID 4627 - Group membership information
• Event ID 4648 - A logon was attempted using explicit credentials
• Event ID 4697 - A service was installed in the system
• Event ID 7045 - A service was installed in the system
• Event ID 4698 - A scheduled task was created
• Event ID 1102 - The audit log was cleared
• Event ID 7036 - The service entered the stopped state
• sc.exe create
• schtasks.exe /create
• powershell.exe -ExecutionPolicy Bypass
• powershell.exe -enc
• whoami /priv
• net localgroup administrators /add
• net group "Domain Admins" /add
• reg add HKLM\SYSTEM\CurrentControlSet\Services
• lsass.exe
• procdump.exe -ma lsass
• rundll32.exe comsvcs.dll, MiniDump

What your security team should do

• Prioritize patch deployment to domain controllers, Active Directory management servers, administrative workstations, jump servers, and internet-facing or high-value Windows servers.
• Roll out the applicable Microsoft cumulative updates across all affected Windows client and server versions and track completion through patch compliance reporting.
• Hunt for signs of recent local privilege escalation, including unexpected local administrator additions, new privileged services, suspicious scheduled tasks, and abnormal credential access tooling.
• Restrict local logon and remote interactive logon rights to only required users, especially on servers and administrative systems.
• Enforce application control or attack surface reduction controls to prevent untrusted local binaries and scripts from executing.
• Monitor for post-exploitation behaviors such as LSASS access, security tool tampering, creation of persistence mechanisms, and lateral movement from newly compromised hosts.
• Because exploit maturity is currently reported as none and the issue is not in CISA KEV, use risk-based prioritization, but do not defer patching on systems that process credentials or support Active Directory administration.