CVE-2025-62468 Windows Defender Firewall Information Disclosure Patch Guide

Microsoft flagged a new information‑disclosure bug in the Windows Defender Firewall Service — tracked as CVE‑2025‑62468 — describing an out‑of‑bounds read that can allow an authorized local actor to disclose sensitive memory, and it appears in Microsoft’s December 9, 2025 security rollup alongside dozens of other Windows patches.

Background​

The CVE was added to public trackers on December 9, 2025 and is cataloged as an information‑disclosure vulnerability in the Windows Defender Firewall Service (the host‑side service that implements Windows’ packet‑filtering and connection‑management policies). Public aggregators summarize the underlying problem as a buffer over‑read (CWE‑125): code reads past an allocated buffer, potentially returning kernel or process memory to an attacker-controlled context. This advisory was published as part of Microsoft’s December security updates, which bundled multiple Windows kernel and user‑mode fixes. Independent coverage of the December patch set includes CVE‑2025‑62468 within the list of “Important” information‑disclosure items that month.

Why this matters now​

Information‑disclosure bugs are frequently underestimated because they do not directly grant code execution. In practice, however, leaks of kernel or service memory can reveal secrets (tokens, hashes, session data), leak layout information (helpful to bypass ASLR/CFG), or otherwise provide reconnaissance that accelerates full compromise chains. In the current threat climate — where chained vulnerabilities and layering of primitives are common — even a local information leak in a privileged service is operationally valuable to attackers.

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Technical summary and what is known​

• Vulnerability ID: CVE‑2025‑62468.
• Affected component: Windows Defender Firewall Service (service that enforces firewall policy and network filtering).
• Class: Out‑of‑bounds read (buffer over‑read, CWE‑125).
• Impact: Information disclosure — attacker can read memory beyond intended boundaries.
• Attack vector: Local (requires an authorized local user context). Public feeds indicate the attack cannot be triggered remotely without prior local access.
• CVSS v3.1 (public aggregation): 4.4 (Medium) with vector approximated as AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N in at least one public tracker; note that PR:H indicates the public vector strings vary in feeds, and that precise vector details should be validated against Microsoft’s Update Guide for your build.

What is verified vs. what is unclear​

Verified: independent aggregators list the CVE and classify it as an out‑of‑bounds read that leads to an information‑disclosure impact; Microsoft’s Security Update Guide has an entry for the CVE (the canonical source for KB mappings and per‑SKU patches), and the advisory was distributed with December’s patch set. Unverified / flagged for caution: there is no public proof‑of‑concept or technical write‑up in authoritative vendor advisories at the time of publication, and public feeds show minor inconsistencies in the published CVSS vector strings and privilege requirements. These ambiguities mean defenders should treat vendor advisories as authoritative for remediation details, and not assume the exact exploitation preconditions beyond the high‑level description.

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How the bug could be abused (practical attack models)​

An out‑of‑bounds read in a privileged service like Windows Defender Firewall Service is principally an information‑disclosure primitive. In realistic attacker scenarios this can be used in three complementary ways:

• Reconnaissance: leaking memory that contains credentials, session tokens, or configuration data which can be re‑used to access other services or impersonate a user.
• Exploit facilitation: returning heap or stack pointers and layout information that reduces the difficulty of later memory‑corruption exploitation (for example, improving reliability of a separate use‑after‑free or heap overflow exploit).
• Chaining: combining the disclosure with another vulnerability (local EoP or a remote attack against a different component) to escalate a foothold into a complete compromise.

Because the affected service runs with elevated privileges and mediates network traffic, the confidentiality impact is where the operational pain appears even if the flaw itself does not let an attacker run arbitrary code by itself. This pattern is consistent with prior Windows information‑disclosure advisories in 2024–2025 and is emphasized in community operational guidance.

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Exploitability and urgency: what defenders should assume​

Public trackers for CVE‑2025‑62468 list a local attack vector and do not show remote exploitation reports at time of disclosure. That said:

• The presence of a Microsoft advisory and vendor fixes increases the urgency to patch because vendor‑published fixes are strong confirmation that a real defect existed.
• The lack of a public PoC does not mean no private exploit exists; sophisticated attackers often retain exploit code for targeted campaigns. Treat the absence of PoC as uncertainty, not as safety.
• Operational risk becomes higher in environments where unprivileged users or untrusted services run on endpoints with access to the Windows Defender Firewall Service, or where local access is already possible (e.g., via compromised user accounts or malware).

For most organizations the practical risk posture is Medium but context‑dependent: on shared systems, developer workstations, jump servers, or any host where a low‑privilege process can be run by an attacker, the CVE becomes more urgent.

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Confirming details: authoritative mappings and KBs​

Microsoft’s Security Update Guide (MSRC) is the authoritative source for per‑SKU mapping of CVE → KB → update package. Public aggregators and community summaries are useful for triage and context, but operations teams must use MSRC and the Microsoft Update Catalog or their WSUS/Intune pipelines to determine the exact package for each Windows build in their estate. Some MSRC pages require a fully rendered browser session to display the KB mapping cleanly, so teams should open the MSRC entry in a browser rather than relying solely on automated scrapers.

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Detection and hunting: practical telemetry to collect​

Early detection of exploitation attempts for information‑disclosure bugs is difficult because the primitive can be quiet and subtle. Still, defenders can prioritize signals that tend to correlate with local reconnaissance or exploit attempts:

• Endpoint: unusual reads or crashes in Windows Defender Firewall Service processes, elevated service dumps, or repeated application faults correlated to firewall service restarts.
• Process telemetry: unexpected child processes spawned from services that normally do not create many children, or anomalous handle accesses to firewall‑related objects.
• Network: if local exploits are chained to network callbacks, watch for out‑of‑pattern outbound connections that start shortly after suspicious local activity.
• EDR hunts: search for recent local interactive sessions followed by injection patterns, token theft indicators, or suspicious DeviceIoControl/IOCTL sequences that interact with firewall or networking components.

Operational playbooks assembled during the 2025 Windows advisory waves recommend increased logging and short‑term telemetry intensification (7–14 days) after a patch rollout because attackers often scan and attempt automated exploitation in that window.

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Mitigations and emergency controls​

The single most reliable mitigation is to install Microsoft’s security update that addresses CVE‑2025‑62468 for your platform and build. MSRC is the authoritative mapping to the exact KB; deploy those KBs through your normal patch channels (WSUS, SCCM/ConfigMgr, Intune, Microsoft Update Catalog). If immediate patching is not possible, consider these compensating controls:

• Reduce the attack surface: limit interactive user access on high‑value hosts, remove unnecessary local accounts, and tighten group membership for local admins.
• Process containment: restrict or instrument which processes are allowed to interact with service APIs; use application allow‑listing (WDAC/AppLocker) where practical.
• Isolation: temporarily isolate or harden systems where untrusted code runs (developer workstations, CI agents, shared build servers).
• Network controls: while the vulnerability is local, network segmentation and filtering still reduce the ability of attackers to pivot from a compromised user system to other critical hosts.
• Monitoring and capture: increase EDR and SIEM sensitivity for the indicators described above, and plan for memory/dump capture if suspicious activity appears.

Administrators should avoid workarounds that involve disabling core security services globally; instead, follow targeted containment and the vendor’s remediation guidance. The MSRC Update Guide is the canonical patch action; other mitigations are interim and context‑specific.

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Patching guidance: a pragmatic rollout plan​

1. Identify affected systems: query inventories and endpoint management to list hosts that include the Windows build and SKU that the MSRC entry maps to. Use WSUS/ConfigMgr queries or PowerShell automation to enumerate candidate hosts.
2. Stage and pilot: deploy updates to a representative pilot ring that includes jump hosts and a subset of administrative workstations. Validate functionality after the update.
3. Prioritize internet‑facing and high‑privilege hosts: if any hosts expose firewall control endpoints or host security tooling, prioritize them for earlier rollout.
4. Full rollout: after pilot validation, proceed with enterprise‑wide deployment according to normal policy. Track installation status (Get‑HotFix or Windows Update history) and require reboots where necessary.
5. Post‑patch monitoring: keep heightened telemetry for at least two weeks and hunt for indicators of attempted exploitation prior to patching.

Because MSRC is the final authority for KB mapping, automation that pulls MSRC entries directly into your patch orchestration tooling reduces human error when mapping CVEs to SKUs and KB numbers.

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Risk analysis: strengths of the public disclosure and remaining hazards​

Notable strengths

• Vendor action: Microsoft published an advisory entry and shipped fixes as part of the December update cycle, which is the strongest operational signal that the issue exists and is addressed. This enables straightforward remediation at scale.
• Clear vulnerability class: multiple independent aggregators agree on an out‑of‑bounds read leading to information disclosure, so defenders can prioritize based on a concrete weakness class (CWE‑125).
• Triage guidance available: community playbooks and incident‑response guides produced during 2025’s advisory waves provide practical steps for containment, detection and patch deployment.

Potential risks and caveats

• Ambiguous exploit preconditions: public feeds differ slightly in the CVSS vector wording and privilege requirements, which can confuse triage if teams rely solely on aggregator metadata rather than MSRC. Confirm in MSRC before acting.
• No public PoC: although the absence of public exploit code reduces immediate public weaponization risk, it does not exclude private exploitation by advanced adversaries. Maintain a conservative posture.
• Chaining potential: an information leak in a privileged service can serve as a force multiplier when combined with other local or remote vulnerabilities. Patch and harden proactively.

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Recommendations for Windows administrators (concise checklist)​

• Map CVE‑2025‑62468 to the correct KB(s) for your OS builds using Microsoft’s Security Update Guide; do not rely exclusively on third‑party mirrors.
• Prioritize patch deployment to internet‑facing hosts, jump servers, admin workstations, and systems that run untrusted code.
• If immediate patching is impossible, apply compensating controls: reduce local privileges, tighten application allow‑listing, and isolate high‑risk endpoints.
• Increase logging and EDR/SIEM hunts for firewall service crashes, suspicious IOCTL sequences, and abnormal process tokens or Service‑spawn behavior for 7–14 days post‑patch.
• Maintain a tested rollback and rebuild playbook for suspected compromise: preserve volatile evidence, isolate hosts, and rebuild from known‑good images if intrusion is confirmed.

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Final assessment and editorial note​

CVE‑2025‑62468 is not a headline‑grabbing remote code‑execution zero‑day, but it is a meaningful, vendor‑confirmed information‑disclosure flaw in a privileged Windows service that should be treated seriously. The presence of a Microsoft advisory and an available patch makes remediation actionable; organizations should not delay applying the vendor fixes and must validate the per‑SKU KB mappings before widespread deployment. Public trackers and community playbooks provide helpful operational context, but MSRC remains the authoritative reference for the exact update packages to deploy. Administrators who follow a conservative, prioritized patch plan — inventory, pilot, remediate, and hunt — will reduce the chance that a quiet information leak like this becomes the foundation for a larger, chained compromise. The practical maxim remains unchanged: vendor patches + layered compensations + heightened telemetry = best defense.

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Conclusion
CVE‑2025‑62468 reinforces a recurring security lesson: information‑disclosure vulnerabilities are rarely harmless footnotes. When they appear in privileged, long‑running services they give attackers reconnaissance and leverage that can convert local footholds into full compromises. Patch promptly, verify KB mappings in Microsoft’s Security Update Guide, harden local privileges, and keep detection and hunting elevated during the critical post‑patch window.

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Source: MSRC Security Update Guide - Microsoft Security Response Center