CVE-2026-50365

What it actually does

This vulnerability is an improper authentication flaw in the Windows RPC API that can allow an unauthenticated attacker on an adjacent network segment to bypass expected RPC authentication controls and elevate privileges. Successful exploitation could grant high-impact access to confidentiality, integrity, and availability on affected Windows client and server systems. The attack is network-adjacent rather than fully remote over the internet, requires low attack complexity, and the CVSS vector indicates some user interaction is required.

Why it matters to the business

Compromise of Windows RPC authentication can let an attacker move from local or adjacent network access to elevated control of Windows endpoints or servers, creating risk of data theft, service disruption, malware deployment, lateral movement, and domain-impacting compromise if privileged systems are affected. The vulnerability affects many supported Windows desktop and server versions, including Windows 10, Windows 11, and Windows Server releases from 2012 through 2025, so enterprise exposure may be broad. It is not currently listed in CISA KEV, has no reported ransomware association, and has low EPSS at this time, but the privilege-escalation impact is high enough to warrant timely patching through standard Windows update processes.

How an attack unfolds

An attacker first obtains access to the same local or adjacent network as a vulnerable Windows host, such as through Wi-Fi proximity, a compromised internal device, VPN-adjacent access, or another foothold on the LAN. The attacker then identifies Windows systems exposing RPC services and attempts to interact with the vulnerable RPC API in a way that bypasses expected authentication checks. Because the vulnerability requires user interaction according to the CVSS vector, exploitation may involve causing a user or service context on the target system to initiate or accept a relevant RPC interaction. If the authentication bypass succeeds, the attacker can gain elevated privileges on the target system, then use those privileges to disable defenses, access protected data, create persistence, or pivot to other systems. No public exploit maturity or named threat actor activity is currently reported for this vulnerability.

How to fix it

Apply the relevant Microsoft security updates for all affected Windows client and server versions as soon as they are available through Windows Update, Microsoft Update Catalog, WSUS, Intune, SCCM, or other enterprise patch management tooling. Because no exact fixed build numbers were provided, verify remediation against Microsoft’s official security update guidance for this vulnerability and confirm the installed cumulative update level is equal to or newer than the release containing the fix. Prioritize domain controllers, Windows servers, jump hosts, administrator workstations, shared workstations, and systems on exposed or high-risk LAN segments. Where immediate patching is not possible, reduce exposure by restricting RPC access to trusted subnets, enforcing host firewall rules, disabling unnecessary RPC-exposed services, segmenting untrusted networks such as guest Wi-Fi, and monitoring for abnormal RPC activity. Do not rely on network mitigations as a permanent substitute for patching.

How to confirm the fix worked

Confirm each affected system has installed the Microsoft cumulative update or security update that remediates this vulnerability. Validate using centralized patch inventory, Windows Update history, WSUS/SCCM/Intune compliance reports, and local checks such as installed hotfix or build information. Confirm vulnerable Windows versions, including Windows 10, Windows 11, and Windows Server 2012 through 2025, are either patched, isolated, or retired. From a network perspective, verify that RPC exposure is limited to expected management paths and trusted network segments. Where feasible, run authenticated vulnerability scans after patch deployment to confirm the CVE is no longer reported. Review firewall policy and segmentation controls to ensure adjacent-network attackers cannot freely reach RPC services on critical Windows systems.

Typical attack path

1. Gain access to an adjacent network segment or local LAN where vulnerable Windows systems are reachable.
2. Discover Windows hosts and exposed RPC-related services using network scanning or service enumeration.
3. Trigger or entice the required user interaction needed for the vulnerable RPC workflow.
4. Send crafted RPC traffic that abuses the improper authentication condition.
5. Obtain elevated privileges on the affected Windows system.
6. Use elevated access to collect credentials, modify security settings, deploy tooling, or move laterally.

How to detect it

There are no public, CVE-specific indicators or known exploitation artifacts reported from the provided data. To assess possible prior exploitation, review Windows Security, System, PowerShell, Windows Defender, endpoint detection, firewall, VPN, wireless, and network telemetry for suspicious activity originating from adjacent network ranges around RPC, SMB, and administrative service traffic. Focus on unusual inbound connections to Windows RPC services, unexpected authentication attempts, privilege changes, new local administrator accounts, new or modified services, suspicious scheduled tasks, endpoint protection tampering, lateral movement from peer workstations, and anomalous logon patterns. Useful Windows events to correlate include successful and failed network logons, special privilege assignment, account creation, group membership changes, service installation, scheduled task creation, firewall rule changes, and security log clearing. Because exploitation may require user interaction, correlate suspicious RPC activity with user prompts, unexpected application behavior, helpdesk reports, or endpoint alerts occurring shortly before privilege changes.

What your security team should do

• Prioritize patch deployment to Windows servers, domain controllers, administrative workstations, and systems on shared or less-trusted network segments.
• Use enterprise patch tooling to identify all affected Windows 10, Windows 11, and Windows Server systems and track remediation to completion.
• Restrict inbound RPC access with Windows Defender Firewall and network segmentation so only trusted management systems and required peers can connect.
• Increase monitoring for unusual RPC, SMB, endpoint privilege escalation, new local administrator membership, service creation, and suspicious logon activity from adjacent network ranges.
• Review guest Wi-Fi, VPN, lab, OT, and branch-office networks for paths that could give an attacker adjacent access to Windows systems.
• If patching must be delayed, apply compensating controls such as isolating high-value hosts, disabling unnecessary services, and tightening local administrator controls.
• Reassess priority if public exploit code appears, EPSS rises, or the vulnerability is added to CISA KEV.