Microsoft’s advisory for CVE-2025-59211 documents an information disclosure flaw in the Windows Push Notification Core that allows a low‑privilege, authorized local actor to obtain sensitive data from the system — a vulnerability Microsoft classifies as local, low‑privilege, high‑confidentiality impact and scores as CVSS 3.1 5.5 (Medium).
Windows Push Notification Core is a system component responsible for delivering native push notifications to Windows apps, synchronizing notification state, and brokering message metadata between cloud services and local applications. Because it mediates messages and often touches user and system-level metadata, bugs in its processing paths can expose internal state or cached secrets if buffers, object lifetimes, or access checks are mishandled.
Microsoft’s update guide entry for CVE-2025-59211 characterizes the issue as an information‑disclosure vulnerability that requires local access to trigger and that can expose sensitive data to an unauthorized actor via the Push Notification Core. Public vulnerability aggregators mirror that description and list the vector as local (AV:L) with low privileges required (PR:L) and no user interaction required.
Why this matters: even when a bug is local‑only, information leaks from privileged or semi‑privileged services are frequent stepping stones for escalation, credential theft, and lateral movement. Leaked memory fragments, tokens, or configuration artifacts can be weaponized by attackers who already have a foothold — turning a minor local bug into a full compromise when chained with other issues.
For defenders: treat this as a high‑priority patch for the right hosts (shared/VDI/build systems and any machine where untrusted local users exist). Patch first, hunt second, and harden user privileges and process controls while you close the window of exposure. If any signs of suspicious activity appear prior to patching — unexpected memory reads, abnormal process calls to notification services, or odd installer behavior — escalate to incident response immediately and preserve forensic evidence for analysis.
Caveat: Where the advisory omits precise technical root cause, any detailed explanation of exploitation mechanics is necessarily inferential and based on historical patterns for similar Windows information‑disclosure bugs. Those inferences are used here to create pragmatic detection and mitigation guidance, but specific exploitable primitives (exact IOCTL, function name, or memory layout) must be confirmed against official vendor disclosures or authoritative research once published.
Source: MSRC Security Update Guide - Microsoft Security Response Center
Windows Push Notification Core is a system component responsible for delivering native push notifications to Windows apps, synchronizing notification state, and brokering message metadata between cloud services and local applications. Because it mediates messages and often touches user and system-level metadata, bugs in its processing paths can expose internal state or cached secrets if buffers, object lifetimes, or access checks are mishandled.Microsoft’s update guide entry for CVE-2025-59211 characterizes the issue as an information‑disclosure vulnerability that requires local access to trigger and that can expose sensitive data to an unauthorized actor via the Push Notification Core. Public vulnerability aggregators mirror that description and list the vector as local (AV:L) with low privileges required (PR:L) and no user interaction required.
Why this matters: even when a bug is local‑only, information leaks from privileged or semi‑privileged services are frequent stepping stones for escalation, credential theft, and lateral movement. Leaked memory fragments, tokens, or configuration artifacts can be weaponized by attackers who already have a foothold — turning a minor local bug into a full compromise when chained with other issues.
What we know (confirmed details)
- The vulnerability identifier is CVE‑2025‑59211 and is recorded in Microsoft’s Security Update Guide.
- Microsoft’s published metadata describes the flaw as an information disclosure in Windows Push Notification Core, where an authorized local attacker can disclose information locally (i.e., the attack requires code or access on the host).
- The widely cited CVSS v3.1 vector approximates to AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N (local attack vector, low privilege required, high confidentiality impact), with a base score reported at 5.5 (Medium). This scoring is consistent across multiple aggregators.
What remains unverified or incomplete in public reporting
- Public, detailed technical write‑ups (post‑mortems) explaining the exact root cause (for example, whether this is an out‑of‑bounds read, use‑of‑uninitialized memory, or incorrect access control) are not yet widely available. At the time of writing, Microsoft’s short advisory gives the impact class (information disclosure) but not a full technical root‑cause disclosure. Third‑party summaries infer typical classes of root cause (uninitialized buffers, improper length checks, bad marshalling), but those remain inferred until detailed notes or vendor statements appear.
- Precise lists of affected SKUs and KB numbers must be confirmed from the MSRC entry and Microsoft Update Catalog. Because Microsoft’s Update Guide is delivered as a dynamic web application, some third‑party scrapers and feeds may lag or show incomplete metadata — always verify KB mapping in a JavaScript‑capable browser directly against MSRC.
Technical analysis — likely root causes and exploitation model
Microsoft labels CVE‑2025‑59211 as an information disclosure in Push Notification Core; that phrasing is deliberately broad but tells defenders what to expect.Typical technical patterns for this class of bug
- Use of uninitialized resources / out‑of‑bounds reads: A service returns a buffer to user code (or another component) without zeroing it or bounds‑checking lengths. Residual kernel- or process‑memory contents are then disclosed. This is a common pattern for information‑disclosure bugs in Windows subsystems.
- Improper marshalling between kernel and user modes: If the Push Notification Core relies on a driver or privileged service to marshal messages, an incorrect IOCTL contract (wrong lengths, missing validation) can cause kernel memory to be copied to user buffers. Historically, that’s how many local leaks were exploited.
- Access control or type confusion: Where Push Notification APIs accept opaque handles or objects from less‑trusted processes, type confusion or insufficient enforcement can cause a privileged path to disclose metadata it should not. Earlier Push Notification CVEs in Windows have included type‑confusion EoP variants, so this is a plausible pattern.
Attack model for CVE‑2025‑59211
- Preconditions: Local code execution or an authorized local account (low privilege) that can interact with the Push Notification Core APIs or service. Because the vector is local, remote attackers cannot directly trigger this without a separate foothold or a local delivery mechanism (malicious installer, LPE chain, or social engineering).
- What an attacker can gain: Leaked memory fragments may include authentication tokens, cached credentials, app‑specific secrets, TLS session artifacts, or internal pointers that aid further exploitation and bypass of exploit mitigations. Even small leaks can be leveraged for credential theft, forging sessions, or constructing local privilege escalation chains.
- Exploit complexity: Likely low‑to‑moderate. Information‑disclosure bugs are generally easier to weaponize than full remote code execution when the attacker controls input and can scrape outputs. However, reliable exploitation often requires careful probing and data processing to reassemble useful secrets from raw memory fragments.
Operational risk assessment — who should worry, and how urgently
- Local user systems and multi‑user shared hosts are the highest‑priority exposures. If multiple untrusted users (temporary staff, lab users, virtual desktop users) share a Windows host with Push Notification Core accessible, the confidentiality risk rises considerably.
- Enterprise desktops with Endpoint Detection and Response (EDR) and strong least‑privilege policies are at lower risk of an immediate, automated campaign — but the risk remains if attackers can deliver local code or abuse legitimate installers or scripts. For managed fleets, patch deployment lag is the primary operational risk vector.
- Internet‑facing or remotely accessible endpoints are not directly affected unless the Push Notification Core is reachable remotely (rare for a desktop service). However, cloud desktops, remote‑work VDI images, and shared build/test hosts where untrusted users can run code are legitimate concerns. Treat such hosts as high priority for patching.
Recommended mitigations and immediate actions
- Patch immediately: Import the Microsoft update(s) that address CVE‑2025‑59211 into your test ring and push to production quickly. Confirm the exact KB and build mapping from Microsoft’s Security Update Guide and the Microsoft Update Catalog before deployment.
- Reduce local attack surface: Enforce least privilege across endpoints. Disable or remove unnecessary local accounts and restrict which users can install software. Where practical, prevent untrusted users from launching local installers that could invoke Push Notification APIs.
- Harden shared or multi‑user hosts: For VDI, lab, or terminal‑server environments, ensure session separation, restrict account privileges, and limit the ability of session users to query or interact with privileged services in ways not required by their role.
- Monitor and hunt: Create EDR/SIEM hunts for anomalous interactions with the Push Notification service, suspicious process calls that enumerate memory, or unusual accesses to notification broker interfaces. Collect memory snapshots for suspect hosts and preserve logs for forensic review.
- Compensating controls where patching is delayed:
- Enforce application whitelisting (WDAC) and block unsigned or unexpected installers that might attempt to interact with the notification stack.
- Require credential rotation for any high‑value tokens that may have transited the service if exposure is suspected.
- For high‑risk systems, consider temporarily restricting interactive user sessions or moving workloads to patched images.
- Validate mitigations: After patching, confirm the system build matches vendor guidance and that telemetry indicates the update is present. Where MSRC lists multiple KBs for different SKUs, confirm the one you installed corresponds to your exact OS build.
Detection & hunting playbook (practical steps)
- Inventory: Identify machines with Push Notification Core and related services active. On managed Windows fleets, query installed packages and running services to find hosts with the notification broker present.
- EDR rules: Create detection rules looking for:
- Unexpected local process calls to the push notification broker.
- Processes reading large memory regions or calling suspicious IOCTLs tied to notification drivers.
- Sudden creation of child processes from signed system binaries in nonstandard paths.
- Logs and memory captures:
- If you detect suspicious behavior, capture a full memory image of the process for off‑line analysis.
- Preserve Application and System event logs and collect any EDR evidence before remediating.
- Hunt queries (examples):
- List hosts with the Windows Push Notification service installed or active.
- Search endpoint telemetry for calls to relevant APIs or for elevated processes performing bulk memory reads.
- Look for signs of recent secret rotation requests or credential resets that might indicate response to suspected exposure.
Cross‑checks and corroboration — why this analysis is trustworthy
Key claims in this briefing have been corroborated against multiple independent sources:- Microsoft’s Security Update Guide entry for CVE‑2025‑59211 is the primary vendor record and establishes the vulnerability class and the attack vector.
- Independent CVE aggregators and trackers (including CVE Details and community feeds) mirror Microsoft’s description and reported CVSS vector, giving independent confirmation of the classification and severity.
- Community and threat‑intel write‑ups on related Windows Push Notification and privileged service information‑disclosure bugs explain typical exploitation techniques and defensive measures, providing broader context and actionable mitigation guidance that aligns with Microsoft’s high‑level guidance.
Strengths, weaknesses, and risks — critical analysis
Strengths in Microsoft’s approach
- Centralized advisory: The Microsoft Security Update Guide provides a single canonical record for CVE metadata and KB mappings, simplifying enterprise patch management once KBs are captured.
- Timely updates: When vendor patches are released, Microsoft’s distribution channels (Windows Update, WSUS, Update Catalog) allow rapid, managed deployments across different SKUs and servicing branches.
Weaknesses and operational friction
- Minimal public technical detail: Microsoft’s short advisory style helps prevent immediate mass weaponization but reduces the ability of defenders and researchers to fully understand exploit mechanics and detection indicators. That limited disclosure forces defenders to rely on inference and broader behavioral detection rather than precise signatures.
- Dynamic advisory UI and KB mapping friction: Because MSRC uses a dynamic web UI, third‑party scrapers sometimes miss or misreport exact KB mappings; administrators must view the advisory in a browser to confirm the precise update for each OS build. That increases the chance of delayed or incorrect patch mapping in large, diverse environments.
Risk outlook
- Short term: Moderate — local exploitability reduces mass‑exploitation risk, but rapid chaining with other local bugs or post‑compromise modules can elevate the outcome to a major incident.
- Medium term: Elevated risk for shared and multi‑user hosts, and for environments with slow patch cycles. Attackers often weaponize information‑disclosure bugs as reconnaissance primitives to make subsequent privilege escalation much more reliable.
Practical checklist — prioritized actions for IT and security teams
- Immediately open the MSRC Update Guide entry for CVE‑2025‑59211 and capture the KB(s) that apply to your Windows builds. Confirm the package IDs in the Microsoft Update Catalog.
- Deploy updates in your staging/test ring and validate functionality before rolling to production.
- Prioritize patch rollout for multi‑user hosts, VDI pools, lab machines, and build servers.
- Enforce least privilege: review local accounts, reduce install privileges, and ensure users cannot run arbitrary code without approval.
- Implement EDR hunts for suspicious interactions with the Push Notification service; preserve memory snapshots when suspicious activity is found.
- Rotate any sensitive tokens or secrets that may have transited the Push Notification stack if you have reason to suspect exposure.
- Document patch status and report to security leadership; escalate if you observe evidence of exploitation or targeted reconnaissance.
Closing assessment
CVE‑2025‑59211 is a reliable, vendor‑confirmed information‑disclosure vulnerability in Windows Push Notification Core that requires local access to exploit and has a medium CVSS rating driven by high confidentiality impact. The public evidence is consistent: vendors and aggregators agree on the core facts, but Microsoft’s advisory does not publish in‑depth technical details or static KB listings in every scraped feed. That makes vendor confirmation essential for exact patch mapping, and it increases the operational burden on defenders to rely on conservative mitigations until updates are validated and deployed.For defenders: treat this as a high‑priority patch for the right hosts (shared/VDI/build systems and any machine where untrusted local users exist). Patch first, hunt second, and harden user privileges and process controls while you close the window of exposure. If any signs of suspicious activity appear prior to patching — unexpected memory reads, abnormal process calls to notification services, or odd installer behavior — escalate to incident response immediately and preserve forensic evidence for analysis.
Caveat: Where the advisory omits precise technical root cause, any detailed explanation of exploitation mechanics is necessarily inferential and based on historical patterns for similar Windows information‑disclosure bugs. Those inferences are used here to create pragmatic detection and mitigation guidance, but specific exploitable primitives (exact IOCTL, function name, or memory layout) must be confirmed against official vendor disclosures or authoritative research once published.
Source: MSRC Security Update Guide - Microsoft Security Response Center