CVE-2025-50152: Windows Kernel Out-of-Bounds Read and Local Privilege Escalation

Microsoft’s advisory for CVE-2025-50152 documents an out‑of‑bounds read in the Windows kernel that may allow an authorized local attacker to elevate privileges to SYSTEM; independent vulnerability trackers list the flaw with a CVSS v3.1 base score of 7.8 (High) and, until vendor KB mappings are confirmed in each environment, the safest operational stance is immediate patch prioritization.

Background / Overview​

CVE‑2025‑50152 was publicly recorded in mid‑October 2025 and is described by the vendor and multiple third‑party trackers as an out‑of‑bounds read in kernel code. That class of bug (CWE‑125) means a kernel routine reads memory outside an intended buffer boundary — in kernel context this often yields sensitive information disclosure, pointer leaks, or, when combined with other primitives, an elevation‑of‑privilege (EoP) path. Public vulnerability databases mirror Microsoft’s high‑severity rating and classify the attack vector as local rather than remotely exploitable.
Microsoft’s Security Update Guide is the canonical source for the CVE → KB → build mapping that administrators must use to remediate. Third‑party aggregators provide rapid summaries and CVSS scoring, but they frequently omit per‑SKU KB details or lag behind the vendor’s interactive update matrix; defenders must reconcile their patch lists against the vendor’s Update Guide before deployment.

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What the advisory actually says (concise)​

• Vulnerability: Out‑of‑bounds read in Windows kernel code that can be triggered by an authorized local actor.
• Impact: Local elevation of privilege—successful exploitation can permit a low‑privilege process to achieve SYSTEM or equivalent privileges.
• CVSS v3.1 Base Score: 7.8 (High) as reflected in multiple vulnerability indexes.
• Exploitability: Classified as local; there is no authoritative vendor statement indicating remote, unauthenticated exploitation is possible.
• Public exploitation / PoC status: At the time of this analysis there were no widely‑trusted public proof‑of‑concepts or confirmed mass exploitation reports indexed by major trackers. That absence reduces immediate mass‑exploit risk but is not a substitute for patching.

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Why an out‑of‑bounds read in kernel code matters​

Kernel bugs are high‑value to attackers because kernel code executes with maximal privileges and interfaces with broad system state. An out‑of‑bounds read can be more dangerous in practice than it sounds:

• Information disclosure: Reading past a buffer can leak kernel pointers or secrets that defeat kernel address space layout randomization (KASLR) and other hardening measures.
• Exploit chaining: Leaked pointers and memory layout information are commonly combined with separate memory‑corruption primitives (UAF, buffer overflow, race conditions) to convert a read into a reliable write‑or‑code‑execution primitive.
• Privilege escalation: Once kernel addresses or token structures are known, attackers frequently escalate to SYSTEM by manipulating tokens, vtables, or callback pointers.
• Operational impact: SYSTEM compromise permits disabling endpoint defenses, installing kernel‑level persistence, credential theft, lateral movement and full host takeover. These outcomes make local EoP bugs attractive components of larger intrusion chains.

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Technical analysis (what defenders need to know)​

Nature of the bug​

Public summaries identify CVE‑2025‑50152 as an out‑of‑bounds read within kernel logic. The vendor intentionally limits low‑level exploit detail in its advisory to reduce fast weaponization; independent trackers repeat the high‑level classification and CVSS rating but do not publish exploit chains from the vendor entry. This is a common disclosure pattern for kernel advisories.

Likely exploitation model​

Although Microsoft does not publish a step‑by‑step exploit, standard attacker workflows for a kernel OOB read look like this:

• Obtain a local foothold (standard user process, sandbox escape, malicious installer, or compromised account).
• Trigger the vulnerable kernel path so it performs an out‑of‑bounds read that leaks kernel memory (pointers, function addresses, token references).
• Use leaked information to defeat mitigations (KASLR, kernel CFG), achieve reliable heap/allocator steering, or directly locate token objects for impersonation.
• Combine the leak with a memory‑corruption primitive or token modification to escalate to SYSTEM and persist.

This high‑level chain has been the established pattern for many kernel advisories in 2024–2025 and is why even a read primitive commands urgent attention: a leak is the reconnaissance stage that makes later exploitation deterministic.

Exploit complexity and prerequisites​

• Attack vector: Local (attacker must be able to run code or interact with a privileged interface).
• Initial privileges required: Low / non‑admin user is often sufficient for local EoP exploits.
• Attack complexity: Moderate — turning a read into full EoP typically requires additional steps (heap grooming, allocation control, another primitive) but experienced exploit authors can rapidly develop reliable chains once the leak is understood.
• Real‑world implications: Systems that allow untrusted local execution (VDI hosts, multi‑user desktops, developer workstations, RDP/terminal server endpoints) are higher priority because attackers can combine initial footholds with the kernel primitive for full compromise.

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What is known and what is not (verification and caveats)​

Known / corroborated:

• The CVE exists and is listed by Microsoft in the Security Update Guide and mirrored by major CVE trackers.
• Public trackers list the CVSS v3.1 base score as 7.8 (High) and classify the vector as local.
• The vendor has published an advisory entry and shipped security updates in the relevant monthly update cycle; administrators must map their Windows builds to the KB(s) listed in the Update Guide to remediate.

Unverified / not publicly disclosed:

• The advisory does not disclose low‑level exploit code, exact vulnerable function names, device/driver IOCTLs, or per‑CVE exploitation artifacts. Any third‑party claim that lists precise function names or PoC code should be treated as speculative until validated by Microsoft or a reputable researcher.
• At the time of this analysis, there was no authoritative public PoC publicly indexed by major repositories; absence of a PoC does not mean the vulnerability cannot be weaponized.

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Affected systems and patching guidance​

The MSRC Security Update Guide is the authoritative, per‑SKU mapping to the KB(s) that fix CVE‑2025‑50152. Because Microsoft implements this mapping as a dynamic web application, patch planners should use a modern browser or their patch management systems (WSUS, SCCM/ConfigMgr, Windows Update for Business, Microsoft Update Catalog) to confirm the exact KB for each Windows build. Relying solely on third‑party CVE lists risks mis‑mapping updates for heterogeneous estates.
Prioritization guidance:

• Highest priority: Domain controllers, administrative workstations, jump hosts, RDP/VDI servers, and public desktops where local execution by untrusted users or attachments is plausible.
• Medium priority: Workstations used for development and testing that run untrusted builds or download/execute untrusted content.
• Lower priority: Air‑gapped or isolated systems—but even these should be patched on a controlled cadence because attackers may find alternate local footholds.

Patch rollout recommendations (practical):

• Query MSRC Update Guide for CVE‑2025‑50152 and extract the exact KB IDs for each affected build.
• Stage updates in a small test ring for 24–72 hours, then pilot across a representative cross‑section.
• Roll out broadly, starting with high‑value and high‑exposure hosts; verify deployment using your inventory and update reporting tools.
• Revalidate that the expected patched binaries and KBs appear in the update history and telemetry.

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Short‑term mitigations and compensating controls​

When immediate patching is not feasible, apply layered compensations to reduce the chance an attacker can chain a local foothold into a full compromise:

• Enforce strict least privilege: remove unnecessary local administrator rights and limit SeImpersonate/SeDebug privileges.
• Use application allow‑listing (WDAC or AppLocker) to prevent untrusted binaries from executing.
• Harden remote access: limit RDP/VDI exposure, require jump servers and privileged access workstations (PAWs) for administrative tasks.
• Disable or restrict functionality that enables untrusted code execution (e.g., block script execution in user profiles, restrict mount operations where possible).
• Increase monitoring and EDR detection for indicators of local escalation attempts (token duplication, suspicious DeviceIoControl/IOCTL sequences, sudden SYSTEM‑owned process creation).

Important note: Disabling core services to mitigate a kernel bug is usually counterproductive and can break functionality; the vendor patch is the definitive remediation path.

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Detection and hunting: practical indicators​

Because the exploit requires local interaction and often uses kernel primitives, behavioral detection is the most reliable approach:

• Hunt for sudden process spawn patterns: low‑privilege processes unexpectedly creating SYSTEM‑owned services or new scheduled tasks.
• Monitor for token manipulation: events that show token duplication, impersonation, or sudden elevation of privileges immediately following suspicious user activity.
• Collect kernel crash dumps and EDR memory traces: out‑of‑bounds reads and attempted exploitation frequently produce kernel instability or crashes that are detectable in crash dumps.
• Watch for unusual DeviceIoControl activity or frequent IOCTL invocation patterns from non‑privileged processes (if the vulnerable path involves driver IOCTLs).
• Deploy Sysmon/EDR rules to flag sequences like: user process → repeated IOCTL calls → immediate spawn of admin tooling (cmd.exe, powershell.exe) or creation of services.

If compromise is suspected:

• Isolate the host and preserve memory and crash dumps before rebooting when possible.
• Collect EDR telemetry, event logs, and forensic artifacts.
• Rotate credentials and secrets that might have been accessible on the affected host.
• Rebuild compromised hosts if reliable indicators of compromise are found.

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Risk assessment — who should worry most​

This vulnerability primarily threatens environments where an attacker can achieve an initial local foothold. Prioritize remediation for:

• Internet‑facing desktops and public workstations (kiosks, shared devices).
• Virtual desktop infrastructure (VDI) and RDP/Terminal Server hosts.
• Developer workstations and build servers that execute untrusted or third‑party code.
• Hyper‑V hosts and management servers (if the affected kernel path is used in virtualization components; verify per the Update Guide).

While remote, unauthenticated mass exploitation is not the reported vector, local EoP primitives are frequently used in targeted intrusions and ransomware campaigns once initial access is obtained — turning a foothold into a full host compromise.

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Strengths and gaps in public disclosure​

Strengths:

• Microsoft has published an Update Guide entry and released fixes in the relevant update channel, providing a clear remediation route.
• Independent trackers corroborate the CVSS rating and basic impact, giving defenders consistent severity signals.

Gaps / risks:

• Vendor advisories intentionally omit exploit‑level detail; defenders must be cautious when third‑party writeups speculate about precise exploit techniques.
• Third‑party CVE lists sometimes omit the full KB ↔ build mapping or expose it later than Microsoft’s Update Guide, which can complicate rapid, correct patch deployment. Always reconcile with the vendor’s authoritative update matrix.

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Action checklist for IT teams (what to do now)​

• Immediately map CVE‑2025‑50152 to affected builds using Microsoft’s Security Update Guide; obtain the exact KB IDs for your Windows SKUs.
• Patch high‑priority systems first: domain controllers, admin workstations, jump hosts, RDP/VDI servers.
• If patching is delayed, apply compensating controls: WDAC/AppLocker, remove unnecessary local admin rights, restrict RDP access, and isolate high‑value hosts.
• Tune EDR/SIEM rules for local privilege escalation patterns and DeviceIoControl/IOCTL abuses; prepare forensic capture procedures for suspected incidents.
• Validate patch deployment across the estate and confirm the expected KBs and binary versions via inventory tools.

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Final assessment — balancing urgency and pragmatism​

CVE‑2025‑50152 is a confirmed Windows kernel vulnerability with a high severity rating and real operational consequences for hosts where local code execution is feasible. The immediate defensive path is clear: patch quickly and verify. While the vulnerability requires a local foothold and therefore is less likely to enable unauthenticated remote mass compromise, kernel leaks are valuable reconnaissance primitives that enable weaponization; defenders should treat the absence of public PoCs as temporary and not delay remediation.

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Conclusion​

CVE‑2025‑50152 underscores a familiar and uncomfortable truth for Windows defenders: kernel memory‑safety defects, even when described as reads rather than writes, are gateways for attackers who already have some access. The combination of a high CVSS score, the kernel context of the bug, and historical patterns for exploit chaining makes rapid, validated patching the only dependable corrective action. Use Microsoft’s Security Update Guide to identify the precise KBs for your builds, prioritize high‑value and high‑exposure hosts, and harden local execution and privilege policies while you deploy fixes. Vigilant telemetry and readiness to preserve forensic artifacts remain essential should an exploitation attempt be observed.

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Source: MSRC Security Update Guide - Microsoft Security Response Center