CVE-2026-42970 Overview
CVE-2026-42970 is an information disclosure vulnerability in the Windows Push Notifications component. The flaw stems from the use of an uninitialized resource [CWE-200], which allows an authorized local attacker to read memory contents that should not be exposed. Microsoft has published a security update addressing the issue through the Microsoft Security Response Center.
The vulnerability requires local access and low-level privileges. It does not enable code execution or data modification, but it can leak sensitive process memory to a low-privileged user on the affected host.
Critical Impact
An authenticated local attacker can read uninitialized memory from the Windows Push Notifications subsystem, potentially exposing sensitive data resident in process memory.
Affected Products
- Microsoft Windows (Windows Push Notifications component)
- Specific affected builds are enumerated in the Microsoft Security Response Center advisory
- Refer to the Microsoft Security Update for CVE-2026-42970 for the authoritative product list
Discovery Timeline
- 2026-06-09 - CVE-2026-42970 published to the National Vulnerability Database
- 2026-06-09 - Last updated in NVD database
Technical Details for CVE-2026-42970
Vulnerability Analysis
The vulnerability resides in the Windows Push Notifications service, which delivers toast and tile notifications to applications. The component fails to fully initialize a resource before its contents are returned or otherwise observable to a calling process. As a result, residual data from prior allocations remains accessible.
An authorized attacker with the ability to execute code on the local system can invoke the affected interface and recover bytes that were never explicitly written by the service. These bytes may contain fragments of kernel or user-mode memory, including pointers, identifiers, or other process data.
The impact is limited to confidentiality. Integrity and availability are not affected, and exploitation does not yield direct code execution. However, leaked pointer values or secrets can support chained attacks targeting other vulnerabilities on the same host.
Root Cause
The root cause is classified under [CWE-200] (Exposure of Sensitive Information to an Unauthorized Actor), specifically through the use of an uninitialized resource. A buffer, structure, or kernel object is allocated and then returned without being zeroed or fully populated by the producing code path. The consumer reads memory that retains data from an earlier allocation, violating the boundary between security contexts.
Attack Vector
Exploitation requires local code execution as an authenticated user. The attacker calls into the Windows Push Notifications interface with crafted parameters and inspects the returned data for residual memory. No user interaction is required beyond the attacker's own session. Network-based exploitation is not possible because the attack vector is local.
No public proof-of-concept code or in-the-wild exploitation has been reported. Technical specifics of the affected APIs and data structures are referenced in the Microsoft Security Update for CVE-2026-42970.
Detection Methods for CVE-2026-42970
Indicators of Compromise
- No public indicators of compromise have been published for CVE-2026-42970
- Absence of the corresponding Microsoft security update on a Windows host is the primary observable risk indicator
- Unexpected processes interacting with the Windows Push Notifications service (WpnService) under low-privileged user contexts warrant review
Detection Strategies
- Inventory Windows endpoints and compare installed patch levels against the Microsoft advisory for CVE-2026-42970
- Monitor process creation events where non-system processes invoke push notification APIs at high frequency
- Correlate local logon events with subsequent anomalous access to the WpnService or related RPC interfaces
Monitoring Recommendations
- Enable Windows Security and Sysmon logging for process creation, image loads, and RPC calls touching wpnservice.dll and wpncore.dll
- Forward endpoint telemetry to a centralized analytics platform to baseline normal interaction with the push notification subsystem
- Track patch deployment metrics for the June 2026 Microsoft security release to confirm full coverage
How to Mitigate CVE-2026-42970
Immediate Actions Required
- Apply the Microsoft security update referenced in the Microsoft Security Update for CVE-2026-42970 to all affected Windows systems
- Prioritize patching on multi-user systems, terminal servers, and developer workstations where local accounts are most exposed
- Verify patch deployment using configuration management tooling and Windows Update reporting
Patch Information
Microsoft released a fix through its standard Patch Tuesday channel. Administrators should consult the Microsoft Security Update for CVE-2026-42970 for KB numbers, build versions, and download links for each supported Windows release.
Workarounds
- No official workaround has been published by Microsoft; patching is the supported remediation
- Restrict interactive logon and limit the number of users with local accounts on sensitive hosts to reduce exposure
- Enforce least-privilege policies so that compromise of a low-privileged account yields minimal additional value
# Verify the Windows Push Notifications update is installed (PowerShell)
Get-HotFix | Sort-Object -Property InstalledOn -Descending | Select-Object -First 20
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
