CVE-2025-50155: Local Privilege Escalation in Windows Push Notifications (Type Confusion)

Microsoft’s Security Response Center (MSRC) has cataloged CVE-2025-50155 as an Elevation of Privilege (EoP) vulnerability in the Windows Push Notifications Apps component described as “Access of resource using incompatible type (‘type confusion’).” The issue allows an authorized local attacker — an account with valid logon on a target machine — to abuse the Windows Push Notifications stack and elevate privileges locally, potentially reaching SYSTEM-level rights if combined with additional actions. MSRC lists this advisory in its update guide and urges admins to apply the vendor-supplied fixes included in the appropriate cumulative updates.

Background / Overview​

Windows Push Notifications underpin the modern notification platform: two services commonly involved are the Windows Push Notifications System Service (WpnService), which runs as LocalSystem in session 0, and the Windows Push Notifications User Service (WpnUserService), which runs per-user. These services host the Notification Platform and connection providers that interact with the Windows Notification Service (WNS) and present toast, tile, and raw notifications to users and apps. Both services run with elevated privileges and are widely present on supported Windows clients and server SKUs.
The vulnerability class here — type confusion — is a memory-safety flaw where code treats a resource or pointer as one data type while it was actually another. In modern operating systems, type confusion in privileged components can be weaponized to overwrite or redirect execution by making high-privilege code operate on attacker-controlled data structures. When the vulnerable component runs in the system context (such as WpnService running as LocalSystem), successful exploitation of type confusion can lead to privilege escalation to SYSTEM. The vendor summary emphasizes the attack is local and authorized, which limits remote exploitation but retains severe operational impact in many environments.

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Technical analysis​

What “access of resource using incompatible type (‘type confusion’)” means in practice​

Type confusion occurs when the program assumes that memory or an object instance is of one class/type while it actually holds another. That mismatch can lead to:

• Interpreting attacker-controlled data as function pointers or vtable entries.
• Overwriting security-critical fields in kernel-accessible structures.
• Invoking code paths that trust input types and skip validation, enabling unintended privilege operations.

In user-mode services that host privileged behavior — such as connecting to WNS, managing notification channels, or interacting with other system components — a type-confusion error can provide the foothold to corrupt memory or escalate the privileges of a malicious process. The broad attack pattern often looks like:

• Local, authorized actor triggers a specific API or sequence in the Push Notifications stack.
• The stack misinterprets an object or buffer type and dereferences it incorrectly.
• Attacker-controlled memory is used in place of legitimate structures, allowing modification of execution state or credentials.
• The attacker executes code or performs actions as a higher-privileged account (potentially SYSTEM).

Preconditions and exploitation complexity​

Key practical facts affecting real-world risk:

• The attacker must be authorized locally — meaning remote exploitation without credentials or prior foothold is not the advertised vector.
• Exploit complexity for type confusion can vary widely. Some type-confusion bugs require precise memory grooming and timing, others are straightforward to trigger. The vendor advisory provides only limited technical disclosure to reduce weaponization risk.
• The Windows Push Notifications services run as LocalSystem and therefore carry high-impact privileges, increasing the severity of any successful escalation path.

Because this is a local EoP, the most immediate attack scenarios are:

• An attacker who has executed unprivileged code (for example, via malicious macros, phishing, or post-authentication web compromises) uses the EoP to break out of low-privilege constraints.
• Malicious or compromised insiders escalate privileges on a corporate workstation or server.
• Threat actors who have limited access to a managed endpoint chain this EoP with lateral movement and persistence techniques.

How this fits into the recent pattern of Windows memory-safety issues​

Over the last 18 months there has been a noticeable cluster of memory-safety flaws — use-after-free, type confusion, and heap overflows — across multiple Windows components (notification stacks, graphics kernels, MSMQ, Hyper‑V, and others). These vulnerabilities continue to be a primary avenue for local privilege escalation and are often patched in the monthly Microsoft security updates. Industry dashboards and vulnerability trackers show recurring EoP items tied to notification and messaging subsystems, which confirms that privileged, widely present services remain an attractive target surface. (nvd.nist.gov, cisa.gov)

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Affected platforms and severity (what we can verify and what remains uncertain)​

Microsoft’s advisory entry identifies the vulnerability and class but, as is common with MSRC pages, the rendered content is JavaScript-driven; administrators should consult the MSRC update guide for the definitive list of affected SKUs and the exact KBs that contain the fix. The vendor text explicitly classifies the issue as a local Elevation of Privilege vulnerability in Windows Push Notifications Apps.
Public vulnerability databases list prior Push Notifications EoP entries (notably CVE-2022-29125) affecting multiple Windows client and server releases; however, for CVE-2025-50155 the authoritative product/patch matrix should be read directly from MSRC. Where third-party aggregators and community discussion exist, they echo the criticality of EoP bugs in the notification stack, but caution is warranted because product lists and CVSS scores sometimes vary between sources until MSRC/NVD finalize entries. (cvedetails.com, nvd.nist.gov)
Caveat: In a number of the recent Microsoft advisories, the initial advisory text does not include a public CVSS base score or exhaustive CPE list at publication time; NVD and other aggregators may add or adjust severity and CPE data later. When CVSS numbers or precise impacted builds matter for automation, confirm the MSRC advisory and Microsoft Update Catalog entries before making enforcement decisions.

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Immediate actions for system administrators​

Priority: high for endpoints and servers in which local accounts can be created or where users routinely run code as standard users.

• Patch immediately: Deploy the Microsoft updates that address CVE-2025-50155 through normal channels (WSUS, SCCM, Microsoft Intune, or Windows Update). The MSRC advisory and the Microsoft Update Catalog are the authoritative places to find the KB number tied to your product build.
• Inventory and prioritize:
• Identify devices running the Windows Push Notifications services (WpnService and WpnUserService). These services are present on most supported Windows 10 and Windows 11 builds and on many Windows Server SKUs. Inventorying by service name is a fast way to prioritize patching.
• Prioritize devices where local accounts are permitted, where users are allowed to install or run unvetted software, or where developer/test machines are present (these are often targeted first by LPE exploits).
• Temporary mitigation (only if patching cannot occur immediately):
• Consider temporarily disabling the Windows Push Notifications System Service (WpnService) and Windows Push Notifications User Service (WpnUserService) on high-risk or segmented hosts if and only if doing so does not break critical business workflows. Disabling these services reduces the attack surface because the component will not be running to accept the malformed type/object sequence. However, disabling the service can affect cloud-notification delivery and app behaviors. If you test this mitigation, do so on a small set and validate application behavior before wide deployment. (revertservice.com, syxsense.com)
• How to disable (example): services.msc or set the Start value under HKLM\SYSTEM\CurrentControlSet\Services\WpnService to 4. Re-enable only after patching. Document user-impact and rollback procedures. (syxsense.com, batcmd.com)
• Detection and monitoring:
• Monitor for unusual Service Control Manager events indicating crashes or restarts of WpnService/WpnUserService, or for svchost.exe instances with unexpected behavior.
• Look for suspicious child processes spawned from user-space apps or evidence of token manipulation and impersonation attempts in EDR telemetry.
• Deploy or tune EDR rules to alert on local processes attempting to modify svchost-hosted services or to write to global kernel objects.
• Hardening and longer-term controls:
• Enforce least privilege (standard users where possible).
• Apply application control (Windows Defender Application Control or AppLocker) to prevent untrusted code from running.
• Ensure robust patch management and test update deployment in a staging group before broad rollout.
• Limit local admin privileges and use Privileged Access Workstations (PAWs) for administrative tasks.

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Detection, telemetry, and forensic signals​

Type-confusion exploitation is often noisy — exploits that succeed may trigger crashes or abnormal behavior before a final payload runs. Useful telemetry signals include:

• Event ID spikes indicating WpnService or WpnUserService crashes.
• EDR alerts for memory corruption indicators, mismatched module loads, or process injection in svchost-hosted services.
• Signs of privilege escalation attempts: creation of scheduled tasks with SYSTEM context, registry alterations under HKLM with creation times matching suspicious activity, and unexpected service registrations.
• Abnormal authentications or lateral-movement patterns from accounts that recently executed unprivileged code.

Because exploitation paths vary, pairing host telemetry with network monitoring and proactively hunting for sequences commonly used in local privilege escalation chains will improve detection rates.

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Risk assessment — strengths and concerns​

Notable strengths / positive signals​

• Vendor patch availability: Microsoft published an advisory entry and has included vulnerability fixes in update releases; that means administrators have an immediate remediation path.
• Local-only vector limits remote, unauthenticated exposure: an external, unauthenticated attacker cannot trigger the flaw over the network without an initial foothold.

Significant risks and caveats​

• High impact if exploited: Push Notification services run as LocalSystem and therefore make successful exploitation a powerful privilege escalator.
• Widespread presence: WpnService/WpnUserService exist on the majority of supported Windows installations by default, increasing attack surface across large fleets.
• Chaining risk: Because the vulnerability is local and authorized, it can be chained with initial access vectors (phishing, malicious installers, or credential theft) to achieve full compromise.
• Older/EOL systems: End-of-life or unsupported Windows versions may not receive patches; if those systems run WpnService, they remain permanently vulnerable until replaced or isolated. Public aggregator data for related Push Notifications vulnerabilities historically lists broad platform coverage; therefore treat older builds as high-risk until proven otherwise. (cvedetails.com, nvd.nist.gov)

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Practical, prioritized checklist (for rapid operations)​

• Patch first: Deploy Microsoft updates for CVE-2025-50155 to all applicable endpoints and servers, starting with high-risk groups (domain controllers, admins’ workstations, servers exposed to user logons).
• Inventory services: Query for WpnService and WpnUserService to identify unpatched hosts. Use endpoint management tooling to build the list.
• Harden hosts: Enforce least privilege and app control policies, and restrict local admin rights.
• Monitor and hunt: Look for service crashes, unexpected svchost behavior, and local processes attempting privilege escalation patterns. Tune EDR rules accordingly.
• Temporary mitigation (if required): Where patch rollout is delayed, consider selectively disabling WpnService/WpnUserService after validating business impact; re-enable only after installing vendor patches. Document and test rollback. (syxsense.com, batcmd.com)

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How this advisory affects enterprise security programs​

CVE-2025-50155 is another reminder that privileged Windows services which interface with user-mode data (notifications, messaging, drivers exposed to user processes) are persistent attack surfaces. For enterprise security teams, this means:

• Maintain a rapid patch window for local EoP vulnerabilities and test robust rollback plans.
• Strengthen endpoint controls to reduce the likelihood of local footholds (e.g., configuration management, software allowlisting).
• Increase emphasis on monitoring for anomalous local behavior — not just network-based indicators. EoP bugs are often the equaliser that converts low‑severity footholds into full-blown incidents.
• Prioritize replacement or isolation of unsupported Windows builds, which often remain the weakest link in patching campaigns. Aggregated vulnerability trackers and community advisories repeatedly flag EoP bugs in foundational services; treat them as high-priority items for incident readiness. (cisa.gov, nvd.nist.gov)

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What remains unverifiable and where to confirm details​

• Exact affected builds and KB numbers for CVE-2025-50155 must be confirmed directly in Microsoft’s Security Update Guide and the Microsoft Update Catalog. The MSRC advisory is the authoritative source for patch identifiers; administrators should use the MSRC advisory page or the Microsoft Update Catalog to obtain the precise KBs for their product versions. Because MSRC’s advisory content is delivered via a JavaScript application, automated scrapers may not show the full content; verify visually on the MSRC site or via Microsoft’s update feeds.
• CVSS base score and NVD enrichment for CVE-2025-50155 may be assigned or revised after Microsoft’s initial disclosure; check the NVD and vendor advisories before updating automated risk scoring. Historical patterns show these values can be updated post-publication by third-party databases.

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Final analysis — balancing urgency with operational reality​

CVE-2025-50155 is a serious, high-priority local elevation-of-privilege issue because it targets the Windows Push Notifications stack that runs with system-level privileges by default. The immediate operational imperative is simple and unchanged from past similar advisories: patch as soon as possible, monitor for suspicious local activity, and apply short-term mitigations where necessary and safe. The local-only vector reduces remote, unauthenticated risk but does not materially diminish the overall operational severity — attackers commonly use such EoP flaws to escalate privileges post-intrusion.
Administrators should avoid knee-jerk, platform-wide service removals without testing; however, in tightly controlled environments or where immediate patching is impossible, selectively disabling WpnService/WpnUserService can be a valid stop-gap when paired with documented impact analysis and re-enablement plans. Combine that with endpoint hardening (application control, least privilege), timely patch orchestration, and EDR-focused detection to reduce both the probability and the impact of exploitation.
For definitive guidance on affected SKUs, KB numbers, and the vendor’s recommended update packages, consult Microsoft’s Security Update Guide entry for CVE-2025-50155 and the Microsoft Update Catalog; treat those pages as the primary authoritative source for operational patching.

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CVE-2025-50155 underscores the persistent challenge of memory-safety in large, complex operating systems: even seemingly auxiliary services—notifications and messaging — can become critical escalation vectors when they run with system privileges. The practical defense remains unchanged: vigilance, rapid patching, least privilege, and layered detection are the most reliable ways to blunt the operational effect of these vulnerabilities.

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Source: MSRC Security Update Guide - Microsoft Security Response Center