CVE-2026-69294: Microsoft COM Information Disclosure Flaw

CVE-2026-69294 Overview

CVE-2026-69294 is an information disclosure vulnerability in Microsoft Component Object Model (COM) for Windows. The flaw stems from error messages that contain sensitive information [CWE-209]. An authorized local attacker can trigger these errors to read data they should not have access to. Microsoft published the advisory through the Microsoft Security Response Center (MSRC) on September 8, 2026.

The vulnerability requires local access and low privileges, with no user interaction needed. Successful exploitation impacts confidentiality but does not affect integrity or availability of the target system.

Critical Impact
An authenticated local attacker can obtain sensitive information from Microsoft COM error messages, which may aid follow-on attacks or privilege escalation attempts.

Affected Products

Microsoft COM for Windows (specific builds listed in the Microsoft Security Update Guide)
Windows operating systems that ship the affected COM component
Downstream applications relying on the vulnerable COM subsystem

Discovery Timeline

2026-09-08 - CVE CVE-2026-69294 published to NVD
2026-09-08 - Last updated in NVD database

Technical Details for CVE-2026-69294

Vulnerability Analysis

The issue is categorized as generation of an error message containing sensitive information [CWE-209]. Microsoft COM constructs error responses that expose data intended to remain internal to the operating system or privileged processes. An attacker with a local, authenticated session can invoke COM interfaces in ways that force these verbose error conditions and read the returned content.

Exploitation yields confidentiality impact only. Because the attack vector is local and requires valid credentials, the flaw is most relevant in multi-user hosts, remote desktop environments, and shared workstations. Disclosed information can include memory pointers, object metadata, or configuration details useful for chaining into privilege escalation or sandbox escape attacks.

Root Cause

The root cause is insufficient sanitization of error output produced by COM. Diagnostic data that should be stripped before returning to callers is included in the error message. This pattern maps directly to CWE-209, where sensitive information leaks through exception or error handling paths.

Attack Vector

An attacker authenticates to the target Windows host as a standard user. They then interact with a vulnerable COM interface using a crafted request or malformed parameters that cause the component to emit a verbose error. The error contains sensitive data readable within the attacker's process context. No user interaction is required, and the attack executes entirely on the local system.

No public proof-of-concept exploit is available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. EPSS data as of 2026-09-10 places exploitation likelihood at 0.349% (28.0 percentile).

Detection Methods for CVE-2026-69294

Indicators of Compromise

Unexpected error events from COM subsystems in the Windows Application or System event logs.
Repeated failed COM activation attempts from a single low-privileged user account.
Standard-user processes enumerating or invoking COM interfaces outside normal application behavior.

Detection Strategies

Baseline normal COM interaction patterns per user and application, then alert on statistical deviations.
Correlate error-message-generating COM calls with subsequent privilege escalation or credential-access behavior.
Hunt for local processes performing high-volume COM interface enumeration through interfaces like IDispatch or CoCreateInstance.

Monitoring Recommendations

Enable and forward Windows event logs covering COM, DCOM, and RPC subsystems to a central SIEM.
Monitor for process launches and script activity that programmatically probe COM classes registered in the registry under HKCR\CLSID.
Track logons from standard users on servers where interactive access is uncommon, and review their COM activity.

How to Mitigate CVE-2026-69294

Immediate Actions Required

Apply the Microsoft security update referenced in the Microsoft Security Update Guide for CVE-2026-69294.
Inventory Windows hosts and prioritize patching on multi-user systems, RDS hosts, and jump boxes.
Restrict interactive and remote logon rights for accounts that do not require them.

Patch Information

Microsoft has released a patch through the Microsoft Security Response Center. Refer to the Microsoft Security Update Guide for the specific KB articles and affected build numbers. Deploy the update through Windows Update, WSUS, Microsoft Intune, or your configuration management platform.

Workarounds

No official workaround is documented; applying the vendor patch is the recommended remediation.
Reduce exposure by enforcing least-privilege access and removing unnecessary local user accounts.
Isolate high-value hosts to limit which users can obtain the local access required for exploitation.

bash

# Verify installed Windows updates on a target host
wmic qfe list brief /format:table

# Query recent COM/DCOM related events for triage
wevtutil qe System /q:"*[System[Provider[@Name='Microsoft-Windows-DistributedCOM']]]" /c:50 /rd:true /f:text