CVE-2025-59209 Local Info Disclosure Patch Guide for Windows Push Notification Core

Microsoft has recorded CVE-2025-59209 as an information disclosure vulnerability in the Windows Push Notification Core that can permit a low-privilege, authorized local actor to obtain sensitive information from a host; the advisory classifies the flaw as local-only with a medium CVSS v3.1 score (5.5) driven by high confidentiality impact, and Microsoft administrators are urged to confirm KB-to-build mappings in the Security Update Guide and deploy the appropriate updates urgently.

Background / Overview​

Windows Push Notification Core is a system component that brokers notification delivery between cloud services and local Windows applications. Because it touches metadata, message state, and—at times—cached artifacts, bugs in its processing paths can reveal internal buffers, tokens, or other sensitive material if input validation, marshalling, or buffer handling is incorrect.
Microsoft’s public entry for CVE-2025-59209 classifies the issue as an information disclosure (CWE‑200) and records the CVSS v3.1 vector as AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N with a base score of 5.5, indicating a local attack path requiring only low privileges and no user interaction, but with high confidentiality impact. Independent aggregators reflect the same summary details and publish the CVE as being disclosed on October 14, 2025.
Because Microsoft’s Update Guide pages are dynamically rendered, some third‑party scrapers lag or present incomplete metadata; defenders must therefore consult the MSRC Security Update Guide directly (or the Microsoft Update Catalog/WSUS entries tied to the advisory) to obtain authoritative KB numbers and build mappings before automating patch rollouts.

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Why this matters: operational impact and attacker model​

This is an information disclosure (confidentiality) bug rather than remote code execution or privilege escalation—but that classification understates its operational significance for the following reasons:

• Small memory fragments (tokens, GUIDs, TLS/session artifacts, config snippets) are often sufficient to accelerate post‑compromise activity such as credential reuse, forging of sessions, or breaking KASLR to enable further exploitation.
• The vector is local, so attackers must already have an initial foothold or local access; in multi‑user environments (VDI, labs, developer machines, CI runners) that condition is much easier to satisfy.
• The required privileges are low, and exploitation complexity for information leaks tends to be lower than for full RCE primitives. An automated or scripted local scanner that repeatedly triggers a vulnerable path can quickly harvest leaked artifacts.

In short: CVE-2025-59209 is a reconnaissance-style primitive that greatly increases an attacker’s ability to escalate, persist, or move laterally once they achieve local code execution. Prior advisories for Push Notification and related brokering services show a recurring pattern where disclosure bugs serve as enablers for follow‑on privilege escalation.

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Technical analysis — what the public record confirms and what remains unverified​

Confirmed, high-confidence facts​

• The vulnerability is recorded under CVE‑2025‑59209 and published on October 14, 2025.
• Microsoft classifies it as an information disclosure in Windows Push Notification Core with CVSS v3.1 5.5 and the vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.
• The attack is local-only; remote exploitation without a separate foothold is not indicated by current vendor metadata.

Reasonable, defensible inferences (flagged as such)​

Microsoft’s short advisory style intentionally omits low-level implementation details at initial disclosure. Where root-cause specifics are not provided, experienced analysts draw on historical vulnerability classes in the Windows notification and brokering stack. The likely technical root‑cause categories for a leak in this component include:

• Uninitialized buffer returns or out‑of‑bounds reads where stale memory is copied to user buffers.
• Improper marshalling between privileged service and user processes (incorrect length checks or IOCTL contracts that over-report populated bytes).
• Insufficient access checks or type confusion in brokering interfaces that accept handles/opaque objects from less‑trusted processes.

These are inferences, not vendor confirmations. Microsoft’s advisory does not (yet) state whether the leak is caused by an IOCTL misreport, an off‑by‑one read, a use‑of‑uninitialized-memory, or another specific memory-handling error—so any exploit mechanics beyond the high-level classification must be treated as provisional until a detailed vendor or third‑party technical write‑up is published.

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Affected systems and how to identify them​

Public aggregator listings indicate the vulnerability targets the Windows Push Notification Core present across many modern Windows SKUs. Some industry trackers list affected Windows branches (client and server) in their product tables; however, these third‑party listings are derived from MSRC metadata and may not show the final KB mapping or per‑SKU nuances. The canonical source for exact affected builds and the remediation packages is the Microsoft Security Update Guide and the Microsoft Update Catalog. Administrators should:

• Query inventories for hosts with the Push Notification service or related notification broker components enabled.
• Cross‑check installed OS builds (winver / systeminfo) against the vendor’s KB table to identify the precise patch package required for each host.

Because many enterprise update workflows derive package names and KB numbers from automated feeds, confirm that your feed tool or WSUS synchronizer is rendering the MSRC advisory in a JavaScript-capable context; some automated scrapers miss per‑SKU rows or deliver stale mappings.

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Exploitation model and likely attack chain​

• Initial foothold: An attacker gains local code execution or an ability to run unprivileged code on the target host (malicious installer, user-run executable, dropped payload via phishing, malicious extension).
• Interface probing: The attacker calls the Push Notification Core interface (API, RPC, or IOCTL) that exposes the vulnerable path and collects returned buffers.
• Data harvesting: Returned buffers are parsed to find recognizable secrets (tokens, session state, GUIDs, certificate or key material fragments).
• Follow‑on actions: Extracted artifacts are reused to impersonate services, bypass authentication, pivot to privileged contexts, or feed additional exploits (for example, combining leaked kernel pointers with a local EoP bug to bypass KASLR).

Exploit complexity is likely low-to-moderate for a skilled attacker: while reliably extracting usable secrets from raw memory often requires repeated sampling and processing, the primitives involved (triggering a call and reading a returned buffer) are generally easier to automate than full exploitation chains that require precise heap grooming or race conditions.

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Immediate mitigation and patching guidance (priority checklist)​

Follow this prioritized sequence to reduce exposure quickly and safely.

• Confirm the authoritative KB mapping:
• Open Microsoft’s Security Update Guide entry for CVE‑2025‑59209 and note the exact KB package(s) that apply to each OS build in your environment. Rely on MSRC for the canonical mapping—don’t rely solely on third‑party scrapers.
• Patch in rings:
• Apply the vendor-supplied update in a small pilot ring first. Validate critical application workflows, then expand deployment to production.
• Use WSUS, SCCM (ConfigMgr), Intune, or the Microsoft Update Catalog for offline/air‑gapped machines.
• Prioritize high-risk hosts:
• Shared machines (VDI pools, terminal servers), developer workstations, build/CI servers, and public kiosks should be patched ahead of single-user corporate desktops.
• Hardening where patching is delayed:
• Enforce least privilege (remove unnecessary local install rights).
• Enable application allow-listing (e.g., WDAC) to block untrusted installers that could interact with the Push Notification stack.
• Restrict who can launch developer tools or installers on build agents and CI runners.
• Rotate suspicious secrets:
• If you have reason to believe secrets may have transited the Push Notification layer (for example, local signing keys or integration tokens on developer machines), rotate those credentials once hosts are patched.

Numbered steps for remediation testing:

• Acquire the exact KB for your OS build from the MSRC advisory.
• Apply the KB to a representative test host and reboot if required.
• Run canonical end‑to‑end workflows (builds, notification delivery scenarios, app updates).
• Monitor logs and EDR telemetry for anomalies post-patch.
• Approve and roll out to production in staged waves.

If organizational policy allows, automate patch compliance checks (SCCM/Intune) to ensure the update is present and that the build number reported matches the vendor’s fixed build.

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Detection, hunting, and incident response​

Because the advisory provides minimal technical specifics, detection must rely on behavioral and telemetry signals rather than signature-based indicators.
Suggested EDR/SIEM hunts and telemetry sources:

• Search for abnormal or repeated calls to Push Notification broker APIs or services from user-level processes.
• Monitor for processes repeatedly issuing IOCTLs or large reads against notification-related device objects.
• Alert on sudden memory-dump captures or WER reports tied to the notification broker after suspicious local activity.
• Hunt for processes that spawn children after interacting with push/notification services, especially if those children attempt token manipulation or privileged actions.

Incident response steps if you suspect exploitation:

• Preserve full process memory snapshots of suspicious processes before rebooting.
• Collect Application and System event logs and EDR artifacts.
• Rotate any secrets associated with suspected hosts and isolate affected machines into a controlled environment for forensic analysis.
• If you confirm active exploitation or targeted intrusion, escalate to incident response and follow your breach notification obligations.

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Risk assessment: who should care most​

• High priority: Multi‑user hosts (VDI, shared workstations, build servers) and developer machines that store signing keys or credentials.
• Medium priority: Standard enterprise desktops with strong EDR and limited local install rights.
• Lower priority for immediate remote mass-exploitation: Because the vector is local-only, fully patched remote endpoints are not directly attacked via this CVE alone—however, cloud-hosted VDI or any host that allows untrusted local code remains at risk.

Operational urgency: Patch quickly for systems that are shared, store high-value secrets, or host CI/build pipelines. For single-user corporate endpoints with hardened controls, treat this as a high-priority patch but balance with standard change control and testing.

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Strengths and limitations of public disclosure​

Strengths:

• Microsoft’s Security Update Guide provides a centralized place to obtain the canonical KB mapping and to track remediation status.
• The initial disclosure limits low-level specifics, reducing the immediate risk of mass weaponization while allowing defenders to patch.

Limitations and risks:

• Minimal technical detail reduces defenders’ ability to write precise detection rules or to anticipate exact exploit mechanics.
• Dynamic MSRC pages and third‑party scraping gaps can delay accurate KB→build mapping in large, diverse environments—this increases the chance of incorrect patch targeting or rollout delay.

Because of those gaps, treat vendor messaging as authoritative for patch identification, and treat technical inferences as conservative defensive assumptions until full technical analyses or third‑party research are available.

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Practical playbook: step-by-step for IT/security teams​

• Step 1: Inventory
• Query your estate for installed OS builds and presence of Windows Push Notification components.
• Tag high-value hosts (VDI pools, build servers, developer VMs).
• Step 2: Authoritative mapping
• Pull the exact KB(s) from MSRC for CVE‑2025‑59209 and cross-check the Microsoft Update Catalog entry for each package.
• Step 3: Pilot & validate
• Apply the KB to a small pilot group.
• Validate application compatibility and notification-related workflows.
• Monitor telemetry for anomalies.
• Step 4: Deploy broadly
• Stagger deployments: critical/high-risk hosts first, then general endpoints.
• Step 5: Hardening & monitoring
• Enforce least privilege, enable WDAC where feasible, tune EDR hunts for push-broker interactions.
• Rotate keys/tokens if there is reasonable suspicion they might have been exposed.

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What to watch for next (threat intelligence and research)​

• Vendor follow‑ups: a detailed Microsoft security bulletin or KB article that lists per‑SKU KB numbers and fixed builds is the single most important confirmation step; ensure your patch mapping is based on that authoritative record.
• Third‑party technical write‑ups: expect independent researchers to publish narratives or PoCs over the days/weeks after disclosure; treat any PoC as increasing the urgency to patch.
• Detection content: once researchers publish technical details (function names, IOCTL IDs, or reproduction steps), update EDR detections to include specific indicators of compromise. Until then, rely on behavioral telemetry hunts.

Flag: if any reporting claims precise exploitation primitives or in‑the‑wild campaigns, require at least two independent corroborating sources (vendor advisory, national CERT/CISA, or multiple trusted security vendors) before concluding active exploitation is widespread. This conservative verification standard avoids false positives and misdirected mitigation efforts.

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Conclusion​

CVE‑2025‑59209 is a vendor‑recorded information disclosure in Windows Push Notification Core that is locally exploitable by low‑privilege actors and scored as medium severity (CVSS v3.1 5.5) because of its high confidentiality impact. The immediate, pragmatic response is straightforward: identify affected builds via Microsoft’s Security Update Guide, apply the correct KBs promptly (pilot, validate, then deploy), and combine patching with behavioral hunting and least‑privilege hardening for shared or developer hosts.
Defenders should treat the lack of publicly available low‑level technical detail as a reason for conservative posture—assume the worst-case data exposure until specific artifacts and exploit mechanics are verified—and prioritize environments where local code execution is feasible or where high-value secrets are stored. Rapidly closing the exposure window through tested patches, access controls, and EDR hunts will neutralize the most practical weaponization paths for this CVE.

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Source: MSRC Security Update Guide - Microsoft Security Response Center