CVE-2025-54913 — Windows UI XAML Maps (MapControlSettings)
Race-condition elevation-of-privilege: what admins, developers, and defenders need to knowSummary
- What it is: CVE-2025-54913 is an elevation-of-privilege vulnerability in the Windows UI XAML Maps component (MapControlSettings). The root cause is a race condition — "concurrent execution using a shared resource with improper synchronization" (CWE-362). In plain terms, the component can reach an inconsistent, exploitable state when multiple execution contexts access or modify shared MapControl settings without correct synchronization.
- Impact: a local, authorized user (an authenticated account on the machine) can, under specific timing/conditions, exploit this to escalate privileges on the host.
- Scope: the problem is in the Maps UI component used by UWP / WinUI / WindowsAppSDK-hosted MapControl scenarios (apps that host Windows.UI.Xaml Maps MapControl and interact with its MapControlSettings).
- Action: apply the vendor patch as soon as it is available for your Windows builds and update any apps that embed the affected MapControl components. If you cannot patch immediately, apply the mitigations and defensive measures described below.
Technical background — what a race-condition EoP typically looks like
Race conditions that lead to elevation of privilege generally share a pattern:
- A privileged or sensitive resource (in this case, MapControlSettings or internal state the Maps control relies on) is shared across threads, tasks, or execution contexts.
- Operations that must be atomic (check-then-act sequences, or updates that require consistent memory/state) are performed without adequate locking, serialization, or thread affinity guarantees.
- An attacker with the ability to run code on the machine (an authenticated user-level process) races the component by triggering or orchestrating concurrent accesses that expose a logic flaw (for example, replacing a pointer, changing a flag, or causing a control to be initialized twice in an unexpected state).
- The result can be an out-of-bounds operation, corrupted state, or privilege transition that the attacker uses to gain higher rights (often SYSTEM or similarly privileged context).
- MapControl is a UI control that may bridge multiple subsystems: the XAML UI thread, background tile fetching / renderer threads, and embedded web engines (WebView2 is often involved when a maps control delegates rendering or tile retrieval to an embedded browser context).
- These bridges require marshaling and careful synchronization. Race conditions can arise when component code assumes single-threaded access but code paths are invoked from background worker threads or callback contexts.
- Historically, MapControl and map-related code have had timing, token-passing, and initialization edge cases in complex UI lifecycles — e.g., tokens passed into ExecuteScriptAsync on WebView2, or MapControl initialization sequences that depend on the control being loaded and a web context being ready. Those kinds of multi-context interactions are exactly where race conditions occur.
- Attacker: a local, authenticated user (non-guest) who can run code on the target machine. The vulnerability is not (according to vendor advisory text) a remote, unauthenticated attack.
- Prerequisites: the presence of the vulnerable MapControl component on the host (WinUI / WindowsAppSDK versions or Windows builds that include the vulnerable component) and an attacker process that can interact with or load operations that exercise MapControlSettings (e.g., run a local UWP/WinUI app that uses the MapControl, or otherwise interact with the component via API calls exposed to user processes).
- Goal: escalate privileges from an authenticated user-level context to higher privileges. Exploits of race-condition EoP bugs typically require precise timing and are often non-trivial; however, their presence increases risk to any multi-user or developer/test host where authenticated users have access.
- Local EoP vulnerabilities are significant for multi-user systems, developer machines, build servers, and any environment where authenticated users should not be able to gain administrative or SYSTEM privileges.
- The exploit complexity for race conditions can vary: some are hard to reproduce reliably in the wild (high complexity), others are simpler when a predictable, reproducible sequence exists. Regardless, any confirmed EoP should be remediated quickly.
- Prioritization: treat this as a high-priority patch for servers and workstations used by multiple people, for build/test systems, and for any endpoint that runs local third-party code. For single-user locked-down endpoints, risk is lower but patching is still recommended.
- Patch immediately
- Apply the Microsoft update that fixes CVE-2025-54913 as soon as it is published and validated in your environment. Patches for UI subsystems are delivered through Windows Update / MSRC update channels; schedule deployment via your normal patch-management mechanism and prioritize high‑exposure endpoints first.
- Short-term mitigations if you cannot patch right away
- Restrict access to systems that host developer/test workloads or are accessible to multiple (non-admin) users.
- Reduce the number of accounts with local logon on build machines and servers.
- For managed environments, enforce application control policies (e.g., Microsoft Defender Application Control, AppLocker) to prevent untrusted or developer tool code from running on critical hosts.
- If MapControl is not required on certain machines, consider uninstalling WinAppSDK components or restricting apps that use MapControl until the patch is applied.
- Hardening settings and platform mitigations
- Ensure HVCI (Hypervisor-protected Code Integrity) and Memory Integrity (Core Isolation) are enabled where feasible; they raise the bar for many exploitation techniques.
- Keep Windows Defender / third-party EDR up to date and enforce tamper protection.
- Continue least-privilege practices: avoid granting users local admin, and use administrative bastion hosts for privileged tasks.
Important: do not attempt to exploit the bug; instead, fix the synchronization issues in production code.
At a conceptual level, fixes involve:
- Ensure all access to shared MapControlSettings (or any mutable control state) is properly synchronized. Use appropriate synchronization primitives for the language and runtime:
- C#/WinRT: use lock (a private object) or concurrent collections. Prefer updating UI-affecting state only on the UI dispatcher thread via DispatcherQueue/Dispatcher.RunAsync.
- C++/WinRT: use std::mutex / std::unique_lock or SRW locks depending on context. Ensure lifetime management (smart pointers) is consistent when objects are accessed from multiple threads.
- Avoid exposing sensitive initialization tokens or state to an embedded engine (WebView2) via string concatenation without encoding. Prefer JSON-encoded or otherwise safely-escaped parameter passing.
- Make critical sequences atomic: check-then-act sequences must be protected by the same lock. Where appropriate, use Interlocked operations for single-variable atomicity.
- Use robust lifecycle management: ensure that the MapControl is not referenced after it has been unloaded or destroyed. Guard callbacks/async continuations with weak references and lifetime checks.
- Always marshal UI updates to the UI thread. In C#:
- await DispatcherQueue.GetForCurrentThread().TryEnqueue(() => { / update UI / });
- In C++/WinRT, use the DispatcherQueue to run UI code; avoid touching XAML control state from background worker threads.
- When invoking ExecuteScriptAsync or similar APIs that inject strings into a scripting context, JSON-encode or escape the payload (never concatenate raw tokens into JS).
- Monitor for anomalous local privilege escalations:
- Watch for process creations by nonprivileged users that result in SYSTEM or admin processes they did not start.
- Look for suspicious calls to WinUI/WinAppSDK-hosting processes that are followed by elevation-related events.
- EDR/AV telemetry to collect:
- Process command lines for processes that host MapControl (UWP/WinUI app names, ms-appx URIs, or known app package names that embed MapControl).
- WebView2 script injection calls or suspicious use of ExecuteScriptAsync (these can be noisy; tune for apps that shouldn't be calling it regularly).
- Hunting queries (examples you can adapt for your environment; do not use to exploit):
- Look for process token changes, LUID/token impersonation events, or sudden SYSTEM process spawns originating from user-app processes.
- Track creation of services or scheduled tasks shortly after a user process interacting with UI components.
Incident response checklist (if you suspect exploitation)
- Isolate the affected host(s) from the network.
- Preserve memory and disk images for forensic analysis.
- Identify the initial access vector and the user account used.
- Check for persistence mechanisms added after suspected exploitation (services, scheduled tasks, WMI persistence, startup items).
- Reimage the host if privilege escalation to SYSTEM is confirmed and root cause/malicious payloads are found.
- Apply the patch and update all similar hosts before returning to service.
- Race-condition privilege-escalation vulnerabilities can be weaponized to compromise systems; public exploit code accelerates abuse. The responsible path is to apply vendor fixes and provide developers with safe coding patterns — which is what this article does.
- Inventory apps that embed MapControl or the Maps UI stack. Use application inventory tools to find hosts with WinAppSDK or MapControl-based apps.
- For enterprise apps that embed MapControl, update the app builds to the patched WinAppSDK / WinUI versions once Microsoft publishes fixed runtime libraries.
- Introduce secure development checklists that require:
- Explicit threading/synchronization reviews for UI components.
- Threat modeling for code that crosses process/thread/web boundaries (e.g., UI ↔ WebView2).
- Regular code reviews for areas where tokens or script injection occur.
- Tighten desktop privilege separation: dedicate build/test/dev machines and enforce strict access control and endpoint protections on them.
- Exact builds and CPEs affected (Windows client and server build numbers; WinUI / WindowsAppSDK versions).
- Whether the update is in the OS image, WinAppSDK servicing, or as an independent patch — and the KB number(s).
- Any listed workarounds or mitigations (often vendors will list "no workarounds" but give temporary hardening steps).
- Whether Microsoft has published detection guidance or Defender/EDR signatures.
- Identify hosts running WinUI/WinAppSDK MapControl (inventory).
- Apply Microsoft updates that address CVE-2025-54913 as a top priority.
- Until patched, restrict local authenticated user access to high-value hosts and apply application control where feasible.
- Update developer teams: review UI threading patterns and token-handling code; ensure MapControl updates are marshaled to the UI thread and protected by proper synchronization.
- Tune EDR rules to catch suspicious privilege-escalation sequences originating from UI-hosting processes; preserve logs for any suspect activity.
- I can help you: (a) draft a targeted patch-deployment plan you can use in WSUS/SCCM/Intune for prioritized roll-out; (b) produce a short checklist or slide you can send to your developer teams showing the exact code patterns to replace (locking + UI marshalling examples); or (c) create detection query templates for Microsoft Defender Advanced Hunting and for a generic Syslog/SIEM that you can adapt to your environment.
- This write-up summarizes the vulnerability class and practical defensive advice. For the definitive list of affected versions and the official remediation, consult the Microsoft Security Update Guide entry for CVE-2025-54913 in the Microsoft Security Response Center. Apply the vendor-supplied hotfix, cumulative update, or WinAppSDK update as directed by Microsoft; vendor patches are the authoritative fix.
Source: MSRC Security Update Guide - Microsoft Security Response Center
