CVE-2025-59184: Local Information Disclosure in Windows S2D HA Services

Microsoft has assigned CVE‑2025‑59184 to an information‑disclosure weakness in Windows High Availability Services (the subsystem that underpins Storage Spaces Direct and related cluster features), warning that a low‑privileged, local actor can disclose sensitive information from an affected host; Microsoft has published a security update and industry trackers list the vulnerability with a CVSS v3.1 score of 5.5 (Medium).

Background / Overview​

Storage Spaces Direct (S2D) is Microsoft’s software‑defined storage stack for hyperconverged infrastructure and cluster deployments. It exposes administrative and management surfaces that run with elevated privileges and therefore any flaw that leaks data from those components can be disproportionately valuable to attackers. CVE‑2025‑59184 is classified as an information‑disclosure issue in Windows High Availability Services: the vulnerability’s public records describe an exploitable local attack vector with low complexity and low privilege requirement, and the primary impact is confidentiality loss. Microsoft published the advisory as part of its October 2025 security updates; independent aggregators mirror the vendor’s summary and the CVSS vector.
This feature article unpacks what is known (and what is not), outlines pragmatic mitigation and detection steps for Windows administrators, and weighs the real operational risk to enterprise Windows Server estates and hyperconverged environments.

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What Microsoft and public trackers say​

• The public advisory identifies the vulnerability as an information disclosure in Windows High Availability Services, permitting an authorized local actor to disclose sensitive data. The vendor‑published CVSS v3.1 vector is AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N with a base score of 5.5.
• The disclosure is local only — there is no indication of remote exploitation over the network without prior local access. Public feeds and CVE mirrors list affected Windows Server SKUs (various Server Core and full Server builds across supported Server lines), but administrators must confirm exact build/KB mappings from Microsoft’s Security Update Guide before patching.
• At time of publication there is no widely published proof‑of‑concept (PoC) and no confirmed in‑the‑wild exploitation reported by major tracking services. That reduces immediate mass‑exploit risk but does not change the advice: apply vendor fixes promptly, because information leaks are commonly used as the reconnaissance or chaining step in multi‑stage intrusions.

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Technical context: why an information disclosure in S2D matters​

S2D, HA services, and the value of leaked memory/configuration​

Storage Spaces Direct and associated High Availability Services run privileged code and manage cluster state. When a privileged component inadvertently returns or logs memory or configuration data to less‑privileged callers or files, attackers can harvest:

• Authentication tokens, cached credentials, or service secrets
• Internal endpoints, GUIDs, resource names, or connection strings
• Kernel pointers or structure fragments that aid in defeating memory protection (e.g., KASLR) and weaponizing follow‑on exploits

Even short fragments can materially decrease the complexity of privilege escalation and lateral movement. Public post‑disclosure analysis of similar Windows kernel and clustering bugs repeatedly shows that information disclosure is a common enabling primitive for escalation chains.

Likely classes of root cause (what vendors commonly see)​

Microsoft’s terse advisory language usually avoids low‑level exploit details; however, historically similar disclosures arise from a few implementation mistakes:

• Returning uninitialized buffers or not zeroing memory before returning to user mode.
• Incorrect length reporting in IOCTL or RPC handlers (driver says N bytes returned when only M were filled).
• Excessive logging of internal state or failing to redact sensitive fields before writing to diagnostic logs.
• Insufficient input validation in management APIs that leads to out‑of‑bounds reads.

Because Microsoft’s published entry intentionally omits internal function names or IOCTL codes, the precise defective code path for CVE‑2025‑59184 is not publicly confirmed; treat any specific root‑cause claim as tentative until a researcher or Microsoft provides more detail.

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Scope and affected systems (practical guidance)​

Who should prioritize this CVE​

• Administrators of Storage Spaces Direct clusters, Hyper‑Converged Infrastructure (HCI) hosts, and Windows Failover Cluster nodes.
• Shared multi‑user systems such as VDI hosts, Terminal Servers, CI/CD runners, and developer workstations where low‑privileged users or untrusted code can execute.
• Jump hosts and admin workstations that contain orchestration tooling and credentials for cluster management.

Which SKUs are implicated​

Public trackers list multiple Windows Server builds (Server Core and full Server SKUs across Server 2016/2019/2022/2025 ranges) as potentially affected; however, MSRC’s Update Guide is the canonical mapping for exact CVE → KB → build relationships. Administrators must verify KB identifiers for their exact OS build before declaring systems remediated. Automations that map CVEs to patches should be cross‑checked against the Microsoft Update Guide because the vendor’s advisory pages are often dynamically rendered and can differ by SKU.

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Confirmed facts and cross‑checks​

• CVE‑2025‑59184 exists and is recorded in Microsoft’s update guide and public CVE aggregators.
• The attack vector is local (AV:L). Exploitation requires local code execution or the ability to interact with the High Availability Services on the host. Privileges required are low (non‑elevated accounts can trigger the bug in reported scoring).
• The CVSS v3.1 base score published by Microsoft/trackers is 5.5 (Medium), reflecting high confidentiality impact but no integrity or availability impact in the published vector.
• Microsoft released a security update as part of the October 2025 updates; administrators must consult MSRC to map the CVE to KB(s) for their specific OS build. Automated scrapers sometimes miss that mapping because the Update Guide uses client‑side rendering.

These cross‑checks use independent feeds and the vendor advisory and converge on the same high‑level story: a local information‑disclosure bug affecting Windows High Availability Services with a vendor patch available.

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Practical remediation checklist (24–72 hour playbook)​

• Inventory first
• Use your management tooling (WSUS, ConfigMgr/SCCM, Intune, or third‑party EPM) to enumerate hosts running Storage Spaces Direct, Failover Cluster services, or related cluster roles.
• Map installed OS build numbers (exact build strings) for each host; do not rely on SKU approximations.
• Confirm KB(s) and obtain updates
• Visit Microsoft’s Security Update Guide for CVE‑2025‑59184 and capture the KB(s) mapped to the exact builds in your estate. Because MSRC pages can be dynamically rendered, fetch the entry from a secure admin workstation and record the KB ID(s).
• Test, stage, patch
• Apply the update to a controlled test ring first, then pilot, then production. Follow change control and scheduled reboots required for the patch to take effect.
• Validate post‑patch that cluster services come up cleanly and that management operations function as expected.
• Compensating controls (if patching will be delayed)
• Restrict local logins to cluster nodes: remove unnecessary local accounts, limit SSH/RDP/interactive sessions, and enforce strict administrative separation.
• Harden file ACLs on cluster and log directories so low‑privilege users cannot read diagnostic files. Logs written prior to the patch may contain sensitive entries — rotate and inspect archived logs.
• Post‑patch validation and secrets hygiene
• Confirm KB(s) show as installed via your patch management console.
• If there is a credible suspicion that secrets were exposed (tokens, service account strings, connection strings), rotate those credentials after patching and conduct a focused forensic review.

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Detection and hunting: practical signals to watch​

Because the vulnerability is a local information leak, detection focuses on who is reading privileged artifacts and which processes are interacting with cluster services:

• Monitor for non‑admin processes reading cluster log files or configuration directories (alert on reads where InitiatingProcessAccountName is not SYSTEM or designated admins).
• Look for repeated or anomalous IOCTL/RPC patterns against cluster management binaries originating from low‑privileged contexts.
• Hunt for process parent/child chains where unprivileged processes spawn or interact with elevated management utilities.
• Use EDR telemetry to detect suspicious memory reads, token exports, or unexpected process memory dumps.

Sample hunt approach (generic):

• Query device file events for accesses to Windows\Cluster or cluster log paths by non‑admin accounts.
• Correlate those accesses with process creation events and network activity following the read (possible exfiltration).

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Risk analysis: severity vs. operational impact​

Why a medium CVSS score can understate enterprise risk​

CVSS reflects several dimensions (vector, privileges, user interaction). CVE‑2025‑59184 is scored 5.5 because the vector is local. However, in real environments, even a local disclosure can be catastrophic when:

• Hosts are multi‑tenant or shared (VDI, CI runners, build servers).
• Admin jump hosts or service orchestration machines reside on the same layer.
• Secrets are persistently cached in memory or written into logs that are broadly readable.

In these scenarios a local leak often serves as the reconnaissance piece that makes privilege escalation and lateral movement trivial. Multiple community analyses of recent 2025 kernel and cluster disclosures emphasize that information leakage should be treated with the same operational urgency as escalation vulnerabilities in multi‑user environments.

Likely attacker motivations and end goals​

• Harvest tokens or credentials for lateral movement or persistence.
• Extract configuration or internal endpoints to speed targeted attacks.
• Obtain kernel pointers or structural leaks that enable reliable exploitation of other memory‑safety bugs.

Because the value of leaked fragments can be high, defenders should not assume "information only" equals low business impact.

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Strengths and gaps in public disclosure​

Strengths​

• Vendor acknowledgement and patching: Microsoft published the advisory and shipped updates; that gives administrators an actionable remediation route. Public trackers reproduce the advisory and CVSS vector.
• Clear prioritization: The advisory’s emphasis on confidentiality makes it easier for security teams to prioritize remediation for shared and high‑value hosts.

Gaps and uncertainties (important cautionary notes)​

• Lack of low‑level technical detail in the vendor text. Microsoft’s Update Guide deliberately avoids exploit‑level details; the precise code path (function names, IOCTL IDs, or internal drivers) is not public in the advisory, and independent write‑ups are limited at publication. Treat any specific exploit mechanics as unverified until multiple trusted researchers publish corroborating technical analysis.
• KB→build mapping requires care. Automated feeds can misalign CVE→KB mappings because the Update Guide is dynamic; confirm KB identifiers in an interactive session.
• Historical logs remain a residual risk. Applying the patch does not sanitize past log files that may contain leaked secrets; these must be rotated or sanitized deliberately.

These gaps do not reduce the validity of the advisory; they do, however, increase operational friction for defenders who must be precise during triage and remediation.

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Recommended operational playbook (priority sequence)​

• Immediately identify and inventory all S2D/Failover Cluster hosts and their exact OS builds.
• Retrieve the precise KB(s) for CVE‑2025‑59184 from Microsoft’s Security Update Guide and schedule patching through test → pilot → production.
• If patching is delayed, restrict local access to cluster nodes, tighten log ACLs, and isolate management networks.
• After patching, rotate any long‑lived credentials that could plausibly have been exposed and perform targeted forensic collection on a small set of representative hosts if there is suspicion of prior exposure.
• Implement detection rules to alert on non‑admin reads of cluster logs and anomalous interactions with management binaries.

Numbered remediation steps help operations teams execute under incident pressure and provide traceable milestones for compliance and risk reporting.

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For security teams: incident response & forensics checklist​

• If you suspect a compromise, isolate the host(s) from the network and preserve volatile memory for analysis.
• Collect event logs, EDR telemetry, process dumps, and copies of the cluster logs that could contain leaked artifacts.
• Map pre‑ and post‑patch activity for any non‑admin processes that interacted with management components.
• Rotate keys, tokens, and service credentials that were stored or could have been cached on affected hosts.
• If evidence points to compromise, rebuild from known‑good images after root‑cause analysis.

File and memory artifacts collected early are the highest‑value inputs for determining whether the vulnerability was used as a stepping stone to escalation.

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Final assessment and recommendations​

CVE‑2025‑59184 is a confirmed, vendor‑acknowledged information‑disclosure vulnerability affecting Windows High Availability Services / Storage Spaces Direct, scored 5.5 (Medium) with a local attack vector. Microsoft has published updates; administrators should prioritize mapping the CVE to exact KB(s) for their installed builds and applying the patch quickly — especially for shared hosts, HCI clusters, jump hosts, and developer/build machines.
Operationally, treat this as a high‑urgency remediation for environments where local access by multiple users or untrusted code is a realistic threat. Patch first, then harden local access, sanitize historical logs, and deploy detection rules to spot suspicious reads and management interactions. Because the vendor deliberately omits exploit logistics, do not rely on speculative technical details; instead, base your response on the vendor KB mapping, the high‑level impact, and the pragmatic mitigations above.

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Quick checklist for Windows administrators (one‑page)​

• Inventory cluster and S2D hosts and capture exact build numbers.
• Pull KB mapping for CVE‑2025‑59184 from Microsoft Security Update Guide on a secure admin workstation.
• Apply updates (test → pilot → prod); reboot if required.
• Restrict local logins and tighten ACLs on cluster/log folders while patching.
• Rotate credentials that could have been exposed; sanitize archived logs.
• Deploy EDR hunts for non‑admin reads and anomalous process interactions with cluster services.

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Caveat: this analysis synthesizes Microsoft’s advisory and independent vulnerability aggregators and stock technical patterns for information‑disclosure bugs. The vendor’s Update Guide remains the authoritative source for the exact KB identifiers and per‑SKU remediation steps and should be consulted directly in your patching runbook.
Conclusion: apply the patch, harden local access, and hunt for signs of secret harvesting — because in clustered and multi‑tenant Windows environments, an apparently modest information leak can quickly become the linchpin of a broader compromise.

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Source: MSRC Security Update Guide - Microsoft Security Response Center