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How CVE-2026-50334 Works
CVE-2026-50334 is an information disclosure vulnerability residing in the Windows Notification subsystem — specifically the Windows Push Notification (WPN) service. This component is responsible for delivering toast notifications, tile updates, badge updates, and raw push messages to applications and logged‑on users across Windows 10, Windows 11, and Windows Server editions.
At its core, the flaw stems from improper access control validation when the notification service processes messages that contain sensitive information. The service fails to adequately verify the user context and privilege level of the calling process before granting access to notification payloads or internal notification state data. Under normal operation, notifications are isolated per user session, and only the owning application or user should be able to read the content of a notification. However, due to insufficient permission checks, an authenticated attacker with only low‑privileged local access can manipulate notification handlers or query the notification store to extract data that should remain restricted.
The vulnerability operates at the system service level, meaning it can be triggered without requiring elevation of privileges beyond initial authentication. An attacker who already has a foothold on the machine (e.g., through a limited user account or a previously executed malware) can invoke specific API calls or interact with the notification pipeline to read the content of notifications belonging to other users or applications. The exposed data may include:
– Private messages from communication apps (e.g., Teams, Slack, Outlook)
– One‑time passwords (OTPs) and multi‑factor authentication codes delivered via push notifications
– System alerts containing internal IP addresses, usernames, or configuration paths
– Business‑critical data pushed by line‑of‑business applications
The attack complexity is low, and no user interaction is required — the attacker only needs local access and the ability to execute code. The vulnerability is classified under CWE‑200 (Exposure of Sensitive Information to an Unauthorized Actor) and maps to MITRE ATT&CK technique T1083 (System Information Discovery), as it enables reconnaissance by gathering sensitive data that can be used for further lateral movement or privilege escalation.
Microsoft has acknowledged the issue and released security updates as part of the July 2026 Patch Tuesday. The vulnerability is rated 5.5 (MEDIUM) on the CVSS v3.1 scale, with the vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N — indicating a local, low‑complexity attack that compromises confidentiality but does not affect integrity or availability.
DailyCVE Form
| Field | Value |
|-|-|
| Platform | Microsoft Windows |
| Version | Windows 10 1607/1809/21h2, Windows 11, Windows Server 2019/2022/2025 |
| Vulnerability | Information Disclosure (CWE‑200) |
| Severity | 5.5 (MEDIUM) |
| Date | 2026‑07‑14 |
| Prediction | 2026‑07‑14 (Patch Tuesday release) |
What Undercode Say (Analytics)
CVSS v3.1 Metrics:
- Attack Vector: Local (AV:L)
- Attack Complexity: Low (AC:L)
- Privileges Required: Low (PR:L)
- User Interaction: None (UI:N)
- Scope: Unchanged (S:U)
- Confidentiality Impact: High (C:H)
- Integrity Impact: None (I:N)
- Availability Impact: None (A:N)
- Base Score: 5.5 MEDIUM
Temporal & Threat Intelligence:
- EPSS Score: ~0.05% – 0.07% (low probability of active exploitation in the wild)
- Current Exploit Price Estimation: $5,000 – $25,000 USD
- CTI Interest Score: 0.00 (low attacker interest at time of writing)
- MITRE ATT&CK Mapping: T1083 (System Information Discovery) and T1592 (Gather Victim Host Information)
Useful Bash Commands & Code Snippets
Check if the system is vulnerable by inspecting the installed update (PowerShell):
Get-HotFix | Where-Object { $_.HotFixID -like "KB" } | Sort-Object InstalledOn
List running Windows Push Notification services and their status:
sc query WpnService
Monitor notification events via Event Tracing for Windows (ETW) to detect anomalous access patterns (requires elevated privileges):
logman create trace "NotificationTrace" -p "{Microsoft-Windows-PushNotifications-Platform}" 0xFFFFFFFF -o C:\logs\notification.etl
logman start "NotificationTrace"
Simulate a low‑privileged process attempting to read notification store data (C++ conceptual snippet):
include <windows.h>
include <pushnotification.h> // Hypothetical header
void EnumerateNotifications() {
HANDLE hStore = OpenNotificationStore(L"SID_of_Target_User", NOTIFICATION_READ);
if (hStore) {
NOTIFICATION_DATA data;
while (ReadNextNotification(hStore, &data)) {
printf("Notification Content: %ws\n", data.payload);
}
CloseNotificationStore(hStore);
}
}
Enable verbose logging for the Notification service to detect potential exploitation attempts:
New-Item -Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\PushNotifications" -Name "Debug" -Force Set-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\PushNotifications\Debug" -Name "EnableVerboseLogging" -Value 1
Exploit
An attacker with a local low‑privileged account can exploit CVE‑2026‑50334 by following these steps:
1. Reconnaissance – Enumerate active user sessions and running applications that utilise Windows Push Notifications (e.g., Microsoft Teams, Outlook, authenticator apps).
2. Crafting the Attack – Write a small executable or script that calls undocumented or poorly validated notification API endpoints. The code attempts to open the notification store or subscribe to notification channels belonging to other users by supplying their security identifiers (SIDs) without proper permission checks.
3. Data Extraction – Once the handle is obtained, the attacker iterates over pending and historical notifications, reading the plaintext payload of each message. This may include OTP codes, private chat messages, system alerts, or authentication tokens.
4. Exfiltration – The extracted data is written to a local file or sent to a remote command‑and‑control server via HTTP/S, DNS tunnelling, or other covert channels.
Because the vulnerability requires only low privileges and no user interaction, it can be easily weaponised in malware or used as a stepping stone in a multi‑stage attack. The lack of publicly available exploit code at present does not reduce the risk, as sophisticated adversaries can reverse‑engineer the patch to develop their own exploits.
Protection
- Apply Security Updates – Install the July 2026 Patch Tuesday cumulative update (or later) provided by Microsoft. This update corrects the permission validation logic within the Windows Push Notification service.
- Restrict Local Access – Enforce the principle of least privilege. Ensure that users do not have unnecessary local administrative rights and that standard user accounts are properly segmented.
- Enable Advanced Threat Protection – Use endpoint detection and response (EDR) solutions that can monitor for anomalous behaviour in the notification subsystem, such as unexpected `OpenNotificationStore` calls or unusual process injection into
WpnService. - Configure Mandatory Access Controls – Deploy Windows Defender Application Control (WDAC) or AppLocker to whitelist only trusted executables, preventing untrusted code from interacting with system notification APIs.
- Logging and Monitoring – Enable ETW logging for the PushNotifications‑Platform provider and forward logs to a SIEM. Alert on any process that attempts to read notifications belonging to a different user SID.
- Network Segmentation – Limit the ability of compromised endpoints to exfiltrate data by implementing outbound firewall rules and using proxy inspection to detect unusual data flows.
Impact
Confidentiality Breach – The most direct impact is the unauthorised disclosure of sensitive information. Attackers can read the content of any notification delivered to the system, including personal messages, MFA codes, system health alerts, and proprietary business data.
Lateral Movement & Reconnaissance – The stolen information can be used to map internal network structures, identify high‑value accounts, and uncover further vulnerabilities, significantly aiding subsequent attack phases.
Reputation and Compliance Damage – For organisations handling PII, financial data, or healthcare records, a successful exploitation could lead to regulatory fines, loss of customer trust, and remediation costs.
Cascading Risks – Because the vulnerability operates at the OS level, it can be chained with other privilege escalation bugs to achieve full system compromise. Although the current CVSS score is MEDIUM, the real‑world impact in targeted environments may be considerably higher, especially when notification content includes authentication secrets.
Mitigation Urgency – While no active exploits have been observed in the wild as of the publication date, the low complexity and local attack vector make this vulnerability an attractive target for malware authors. Organisations should prioritise patching all affected Windows endpoints immediately.
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Sources:
Reported By: nvd.nist.gov
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