CVE-2026-42971 Overview
CVE-2026-42971 is an information disclosure vulnerability in the Windows Push Notifications component. The flaw stems from the use of an uninitialized resource, classified under [CWE-200]. An authenticated local attacker can read memory contents that should not be exposed to user-mode callers. Microsoft documented the issue in its security update guide and assigned a CVSS 3.1 base score of 5.5.
Exploitation requires local access and low-privilege authentication. There is no public proof-of-concept, no exploit code in the wild, and the issue is not listed in the CISA Known Exploited Vulnerabilities catalog. The EPSS probability is 0.07%, placing it in the 21st percentile for likely exploitation.
Critical Impact
An authorized local attacker can disclose sensitive memory contents from Windows Push Notifications, potentially exposing data that aids further compromise.
Affected Products
- Windows Push Notifications component (Microsoft Windows) — see the Microsoft Security Update Guide for the affected build list
- Refer to the Microsoft Security Update CVE-2026-42971 advisory for product and build coverage
Discovery Timeline
- 2026-06-09 - CVE-2026-42971 published to NVD
- 2026-06-09 - Last updated in NVD database
Technical Details for CVE-2026-42971
Vulnerability Analysis
The vulnerability resides in the Windows Push Notifications service, which handles toast and tile notifications for applications. The service allocates internal structures that are returned to or readable by local callers. When a code path fails to initialize one or more fields in these structures, residual memory content from prior allocations remains intact. A local user with standard privileges can invoke the affected interface and observe this leftover memory.
The exposed data may include pointer values useful for bypassing Address Space Layout Randomization (ASLR), handles, or fragments of data processed earlier by the service. The vulnerability does not provide code execution or write capability. Confidentiality impact is rated high while integrity and availability are unaffected.
Root Cause
The root cause is the use of an uninitialized resource, mapped to [CWE-200] Exposure of Sensitive Information to an Unauthorized Actor. A buffer or structure field is allocated but not cleared or fully populated before being returned across a trust boundary. The uninitialized bytes carry forward content from previous use of the same memory region.
Attack Vector
The attack vector is local and requires authentication. An attacker who already holds standard user access on the target host crafts requests to the Windows Push Notifications interface and harvests the uninitialized memory returned in responses. Repeated calls allow the attacker to collect varied memory snapshots and reconstruct sensitive values. Network exploitation is not possible, and user interaction is not required.
No verified exploitation code is publicly available. Technical details are described in prose because no validated proof-of-concept exists for this CVE.
Detection Methods for CVE-2026-42971
Indicators of Compromise
- No public indicators of compromise have been published for CVE-2026-42971
- Unusual volume of calls from a single low-privilege process to the Windows Push Notifications service interfaces
- Local processes interacting with WpnUserService or WpnService outside expected application behavior
Detection Strategies
- Audit process telemetry for non-standard binaries enumerating or repeatedly querying push notification APIs
- Correlate Windows Push Notifications service activity with the parent process and signing status to surface unexpected callers
- Apply behavioral analytics that flag low-privilege processes performing memory-disclosure-style repetitive read patterns
Monitoring Recommendations
- Centralize Windows event logs and Sysmon process creation events to a SIEM or data lake for retrospective hunting
- Monitor for unsigned or newly observed binaries invoking push notification COM interfaces
- Track patch deployment status across the fleet to confirm coverage of the Microsoft security update addressing CVE-2026-42971
How to Mitigate CVE-2026-42971
Immediate Actions Required
- Apply the Microsoft security update referenced in the Microsoft Security Update CVE-2026-42971 advisory to all affected Windows systems
- Inventory endpoints and servers running the Windows Push Notifications service and prioritize multi-user and shared workstations
- Restrict local logon rights to reduce the population of users who could invoke the affected interface
Patch Information
Microsoft addressed CVE-2026-42971 through its security update guide. Administrators should consult the Microsoft Security Update CVE-2026-42971 entry for the specific KB articles, affected build numbers, and replacement packages for each supported Windows release. Deploy the update through Windows Update, WSUS, Intune, or the patch management tool used in the environment.
Workarounds
- No vendor-supplied workaround replaces the security update; patching is the supported remediation
- Where patching must be delayed, limit interactive and remote local logon access on affected hosts to trusted administrative users
- Enforce application control to block untrusted binaries from executing on systems pending the update
# Verify the Windows Push Notifications services on a host
Get-Service -Name WpnService, WpnUserService*
# Confirm the latest cumulative update is installed
Get-HotFix | Sort-Object -Property InstalledOn -Descending | Select-Object -First 5
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
