CVE-2026-50350: Windows 10 21h2 Information Disclosure Flaw

CVE-2026-50350 Overview

CVE-2026-50350 is an information disclosure vulnerability in the Windows Trusted Runtime Interface Driver. An authenticated local attacker can read sensitive memory contents that should be isolated from unprivileged callers. Microsoft classifies the issue under [CWE-200: Exposure of Sensitive Information to an Unauthorized Actor].

The flaw affects supported client and server releases including Windows 10, Windows 11, and Windows Server 2025. Exploitation requires local access with low privileges and no user interaction. Successful exploitation impacts confidentiality only, with no integrity or availability effect.

Critical Impact
A low-privileged local user can extract sensitive kernel or driver-managed data through the Trusted Runtime Interface Driver, enabling secondary attacks such as privilege escalation chains.

Affected Products

Microsoft Windows 10 21H2 and 22H2 (x86, x64, ARM64)
Microsoft Windows 11 24H2, 25H2, and 26H1 (x64, ARM64)
Microsoft Windows Server 2025

Discovery Timeline

2026-07-14 - CVE-2026-50350 published to the National Vulnerability Database
2026-07-16 - Last updated in NVD database

Technical Details for CVE-2026-50350

Vulnerability Analysis

The Windows Trusted Runtime Interface Driver mediates communication between user-mode components and trusted runtime services. The vulnerability allows an authorized local caller to obtain data that should remain restricted to higher-privileged contexts. The issue falls under CWE-200, indicating that sensitive information is exposed to an actor not explicitly authorized to view it.

Because the attack vector is local and requires valid credentials on the target host, exploitation typically occurs after an initial foothold. The disclosed data can accelerate follow-on activity, including credential theft, ASLR bypass, or kernel object mapping that supports privilege escalation. Microsoft addressed the flaw through a security update distributed via the standard Windows Update channel.

Root Cause

The root cause is improper isolation of sensitive data returned or exposed through the Trusted Runtime Interface Driver interface. The driver returns or leaves accessible memory contents that should be filtered, zeroed, or restricted based on the caller's trust level. Microsoft has not published low-level technical details in the public advisory.

Attack Vector

An attacker must already have code execution on the target system as an authenticated user with low privileges. The attacker interacts with the driver through its exposed device interface, issuing crafted calls to trigger disclosure of protected memory or state. No user interaction is required, and the attack does not cross a security boundary such as a network. Public proof-of-concept code is not available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

See the Microsoft Security Update Guide for CVE-2026-50350 for vendor-provided technical context.

Detection Methods for CVE-2026-50350

Indicators of Compromise

Unexpected user-mode processes opening handles to the Trusted Runtime Interface Driver device object outside of normal system tooling.
Unusual DeviceIoControl call patterns targeting the driver from non-system binaries or scripting hosts.
Local reconnaissance activity following newly established user sessions on Windows 10, Windows 11, or Windows Server 2025 hosts.

Detection Strategies

Baseline legitimate consumers of the Trusted Runtime Interface Driver and alert on new or unsigned processes issuing IOCTLs to it.
Correlate low-privileged process activity with subsequent privilege escalation attempts or credential access techniques mapped to MITRE ATT&CK T1082 and T1552.
Use behavioral analytics from platforms such as SentinelOne Singularity Endpoint to identify anomalous local process behavior interacting with kernel driver interfaces.

Monitoring Recommendations

Ingest Windows Security, Sysmon, and EDR telemetry into a centralized data lake such as Singularity Data Lake for retrospective hunting across affected Windows builds.
Monitor patch compliance status for the July 2026 Windows security update across all in-scope endpoints and servers.
Track process lineage for tools that enumerate driver interfaces, especially from non-administrative user contexts.

How to Mitigate CVE-2026-50350

Immediate Actions Required

Apply the Microsoft security update referenced in the MSRC advisory for CVE-2026-50350 to all affected Windows 10, Windows 11, and Windows Server 2025 systems.
Prioritize multi-user hosts, jump servers, and Remote Desktop Services servers where local authenticated access is broader.
Verify update installation using Get-HotFix or configuration management reporting.

Patch Information

Microsoft released a security update through the July 2026 Windows Update cycle. The fix modifies the Trusted Runtime Interface Driver to prevent unauthorized disclosure of sensitive data to low-privileged local callers. Refer to the Microsoft Security Update Guide entry for CVE-2026-50350 for KB numbers and per-SKU package details.

Workarounds

No official workaround is documented by Microsoft; installing the security update is the supported remediation.
Restrict interactive and Remote Desktop logon rights to trusted administrators to reduce the population of accounts that can trigger local exploitation.
Enforce application control policies such as Windows Defender Application Control to block untrusted binaries from interacting with kernel driver interfaces.

bash

# Verify installation of the July 2026 cumulative update on Windows
Get-HotFix | Sort-Object -Property InstalledOn -Descending | Select-Object -First 10

# List and audit access to the Trusted Runtime Interface Driver device (example pattern)
Get-CimInstance Win32_SystemDriver | Where-Object { $_.Name -like '*TrustedRuntime*' }