CVE-2026-69684: Windows Error Reporting Information Leak

CVE-2026-69684 is an information disclosure flaw in Windows Error Reporting that exposes sensitive data through error messages. Authorized attackers can exploit this locally to access confidential information. This article covers technical details, affected versions, impact assessment, and mitigation strategies.

CVE-2026-69684 Overview

CVE-2026-69684 is an information disclosure vulnerability in Windows Error Reporting (WER). The flaw stems from the generation of error messages that contain sensitive information [CWE-209]. An authenticated local attacker can leverage the flaw to read data that should not be exposed to their privilege level.

Exploitation requires local access and low privileges. No user interaction is needed. The vulnerability does not affect integrity or availability, but confidentiality impact is high because the leaked data may include memory contents or system state useful for follow-on attacks.

Critical Impact
An authorized local attacker can read sensitive information exposed through Windows Error Reporting diagnostic output, enabling reconnaissance for privilege escalation chains.

Affected Products

Microsoft Windows (Windows Error Reporting component)
Refer to the Microsoft Security Update Guide for the full list of affected Windows versions and builds

Discovery Timeline

2026-09-08 - CVE-2026-69684 published to NVD
2026-09-08 - Last updated in NVD database

Technical Details for CVE-2026-69684

Vulnerability Analysis

Windows Error Reporting collects crash and diagnostic data from user-mode and kernel-mode components. The service generates error messages, dumps, and telemetry describing the fault condition. When these messages include sensitive fields such as memory pointers, tokens, file paths, or contents of process memory, a low-privileged local user can read them and derive information that would otherwise be inaccessible.

The issue is classified under [CWE-209]: Generation of Error Message Containing Sensitive Information. Impact is confined to confidentiality. The attacker cannot modify data or degrade availability through this flaw alone. However, leaked kernel addresses, heap layouts, or credentials materially assist chained exploits targeting privilege escalation.

Root Cause

The root cause is insufficient sanitization of data written into WER error artifacts. Sensitive process or kernel state is embedded in messages accessible to a user context that lacks authorization to view it. Microsoft has not published deeper technical detail beyond the advisory.

Attack Vector

The attack vector is local. An authenticated user with standard privileges triggers or observes a WER event and reads the resulting error message or report. Because no user interaction is required from a second party, the flaw is suitable for use inside automated post-exploitation tooling that harvests reconnaissance data before attempting escalation.

No public proof-of-concept exploit and no active exploitation have been reported. The EPSS probability is 0.469% at the 39th percentile as of 2026-09-10.

Detection Methods for CVE-2026-69684

Indicators of Compromise

Unusual access to %ProgramData%\Microsoft\Windows\WER\ReportQueue\ and WER\ReportArchive\ directories by non-administrative users
Enumeration of wermgr.exe output or repeated invocation of WerFault.exe from user contexts
Access to .wer, .hdmp, or .mdmp files by processes outside standard diagnostic workflows

Detection Strategies

Audit file read events on WER report directories using Windows Security event ID 4663 with SACLs applied
Alert on process creation events (event ID 4688) that spawn crash-inducing child processes followed by WER file reads
Correlate abnormal WER report generation frequency with subsequent local privilege escalation attempts

Monitoring Recommendations

Enable object access auditing on WER report queue and archive directories
Ingest Sysmon event ID 11 (file create) and event ID 1 (process create) data into a SIEM for behavioral analysis
Baseline normal WER activity per host so that outlier read patterns from non-admin accounts surface quickly

How to Mitigate CVE-2026-69684

Immediate Actions Required

Apply the Microsoft security update referenced in the Microsoft Security Update Guide
Inventory Windows endpoints and servers to confirm patch deployment coverage
Restrict interactive local logon rights on sensitive systems to reduce the population of potential attackers

Patch Information

Microsoft has issued a security update addressing CVE-2026-69684. Administrators should consult the Microsoft Security Update Guide for the KB article and build numbers applicable to each supported Windows release, then deploy through Windows Update, WSUS, Intune, or an equivalent patch management tool.

Workarounds

Tighten NTFS permissions on %ProgramData%\Microsoft\Windows\WER\ so that only Administrators and SYSTEM can read report artifacts
Configure WER to submit reports to a controlled corporate endpoint and disable local retention where feasible using the CorporateWerServer Group Policy settings
Limit which users can log on locally to servers exposing sensitive workloads until patching completes

bash

# Configuration example: restrict local WER report access via Group Policy
# Computer Configuration > Administrative Templates > Windows Components >
#   Windows Error Reporting
#     - Disable Windows Error Reporting: Not Configured (keep telemetry)
#     - Configure Corporate Windows Error Reporting: Enabled
#         Server: https://wer.internal.example.com
#         Server port: 443
#         Connect using SSL: Enabled
#     - Do not send additional data: Enabled