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cve

CVE-2025-62215: Windows Kernel Race Condition

Security Substrate

— 6 min read

CVE-2025-62215: Windows Kernel Race Condition

CVE ID: CVE-2025-62215

Severity: HIGH | CVSS: 7.0

Sources: 2 different security sources

Status: ACTIVELY EXPLOITED - Added to CISA KEV Catalog

Let Me Explain What Happened

Let me walk you through something important that's happening right now with Windows systems. Microsoft discovered a vulnerability in the Windows kernel—the core part of the operating system that manages everything—and attackers are already using it in the wild. CISA, our nation's cybersecurity agency, has added this to their Known Exploited Vulnerabilities catalog, which means this isn't theoretical anymore. Real attackers are using this weakness right now to gain complete control over Windows computers.

Here's what makes this particularly concerning: an attacker who already has limited access to a Windows system can exploit a timing problem—what we call a "race condition"—to elevate their privileges all the way to SYSTEM level. That's the highest level of access possible on a Windows machine, giving them complete control.

A Bit More Detail

Think of a race condition like two people trying to use the same bathroom at exactly the same time because the lock doesn't work quite right. In computer terms, it's when two processes try to access the same resource simultaneously, and the system doesn't properly coordinate between them. The Windows kernel has such a flaw, and clever attackers have figured out how to exploit this timing issue to trick the system into giving them administrative privileges they shouldn't have.

This vulnerability was disclosed as part of Microsoft's November 2025 Patch Tuesday, which addressed more than 60 security issues across Windows and related software. According to Krebs on Security, this zero-day flaw affects all versions of Windows, making it a widespread concern for organizations and home users alike.

The Technical Specifics

  • Attack Vector: Local (AV:L) - The attacker needs existing access to the system
  • Attack Complexity: High (AC:H) - Exploitation requires specific timing and conditions
  • Privileges Required: Low (PR:L) - Only basic user access is needed to start
  • User Interaction: None (UI:N) - No victim interaction required
  • Scope: Unchanged (S:U) - Impact limited to the vulnerable component
  • Impact: High confidentiality, integrity, and availability impact (C:H/I:H/A:H)
  • Affected Products: All versions of Microsoft Windows
  • CWE Classification:
    • CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition)
    • CWE-415: Double Free
  • CVSS Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Understanding the Weakness

Let me break down what's actually happening here in a way that makes sense. The vulnerability involves two related memory management issues in the Windows kernel. The primary issue is a race condition—imagine the kernel is trying to manage access to a shared resource, but two different processes can request access at nearly the same moment. If the timing is just right (or just wrong, from our perspective), the kernel can get confused about which process should have access.

The secondary issue, indicated by CWE-415, involves what we call a "double free" condition. This happens when the system tries to release the same piece of memory twice. Think of it like returning the same library book twice—the second time you try to return it, the library's system gets confused because it already processed that return. In computer memory, this confusion can be exploited to corrupt data structures and gain elevated privileges.

What makes this particularly dangerous is that an attacker with even low-level privileges—perhaps they've already compromised a limited user account through phishing or another method—can leverage this vulnerability to gain SYSTEM-level access. That's the equivalent of going from being a guest in someone's house to having the master key to every room, safe, and filing cabinet.

The Timeline and Active Exploitation

Here's how this situation unfolded, based on the sources I've reviewed:

  • November 11, 2025: Microsoft published the vulnerability details as part of their regular Patch Tuesday security updates
  • November 12, 2025: CISA added CVE-2025-62215 to their Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild
  • November 16, 2025: Security researcher Brian Krebs reported on the broader Patch Tuesday release, noting this zero-day was among the critical issues being actively exploited

The fact that CISA added this to their KEV catalog so quickly—within 24 hours of Microsoft's disclosure—tells us that they had credible evidence of active exploitation. CISA doesn't make these additions lightly; their catalog is reserved for vulnerabilities that pose significant risk to federal networks and critical infrastructure.

What You Should Do About This

Let me give you clear, actionable steps to protect your systems. I'll break this into immediate actions and longer-term measures.

  • Right Now (Emergency Response):
    • Check your patch status: Open Windows Update immediately and check if the November 2025 security updates are installed. Don't wait for your normal patching cycle on this one.
    • Review recent privilege escalations: Check your security logs for any unusual account privilege changes, especially accounts that suddenly gained administrative access. Look for Event IDs 4672 (special privileges assigned to new logon) and 4728 (member added to security-enabled global group).
    • Monitor for suspicious SYSTEM-level processes: Use your endpoint detection tools to look for processes running as SYSTEM that were spawned by low-privilege user accounts. This is abnormal behavior that could indicate exploitation.
    • Implement the principle of least privilege: If you haven't already, now is the time to review which accounts have administrative access and reduce that number to the absolute minimum necessary.
  • For the Long Term (Sustainable Security):
    • Apply Microsoft's patches: Install the November 2025 security updates from Microsoft. Visit the Microsoft Security Response Center update guide for specific KB numbers for your Windows version.
    • Enable enhanced logging: Turn on advanced audit policies for privilege use and process creation. This gives you better visibility into potential exploitation attempts.
    • Deploy application control: Consider implementing Windows Defender Application Control (WDAC) or AppLocker to restrict what can execute on your systems, making post-exploitation more difficult for attackers.
    • Segment your network: Ensure that even if an attacker gains SYSTEM access on one machine, they can't easily pivot to other systems. Network segmentation and proper firewall rules are your friends here.
    • Follow CISA's guidance: CISA requires federal agencies to apply mitigations per vendor instructions. Even if you're not a federal agency, following their timeline (typically 21 days for KEV catalog items) is a good benchmark for urgency.

Detection and Hunting Guidance

For those of you running security operations centers or doing threat hunting, here are some specific things to look for:

Windows Event Log Queries:

// Look for privilege escalation events
EventID=4672 OR EventID=4673 OR EventID=4674
| where TimeGenerated >= ago(30d)
| where AccountType == "User"
| where PrivilegeList contains "SeDebugPrivilege" or PrivilegeList contains "SeTcbPrivilege"
| summarize count() by Account, Computer, PrivilegeList
| where count_ > 5  // Adjust threshold based on your environment

Process Creation Monitoring:

// Look for SYSTEM processes spawned by low-privilege users
EventID=4688
| where NewProcessName contains "SYSTEM"
| where SubjectUserName != "SYSTEM" and SubjectUserName != "LOCAL SERVICE" and SubjectUserName != "NETWORK SERVICE"
| project TimeGenerated, Computer, SubjectUserName, NewProcessName, CommandLine

Since this is a kernel-level race condition, you might also see unusual patterns of rapid process creation and termination as attackers attempt to win the race condition. Look for processes that spawn and die repeatedly in quick succession from the same parent process.

Going Deeper: MITRE ATT&CK Context

For those of you who map threats to the MITRE ATT&CK framework, this vulnerability aligns with:

  • TA0004 - Privilege Escalation: The primary tactic, specifically technique T1068 (Exploitation for Privilege Escalation)
  • T1068 - Exploitation for Privilege Escalation: Attackers exploit this kernel vulnerability to elevate from low-privilege user to SYSTEM
  • T1134 - Access Token Manipulation: Once exploitation succeeds, attackers may manipulate access tokens to maintain elevated privileges

Understanding this in the ATT&CK context helps you build detection rules and understand where this fits in a broader attack chain. Typically, attackers would have already achieved initial access (TA0001) and execution (TA0002) before attempting this privilege escalation. They might follow it with credential access (TA0006) or lateral movement (TA0008).

Why This Matters Beyond the Technical Details

Let me put this in perspective for you. Race conditions in the Windows kernel are particularly valuable to attackers because they're reliable across many different Windows versions and configurations. Unlike some vulnerabilities that only work in specific scenarios, a kernel race condition is fundamental to how the operating system works. That's why we're seeing active exploitation so quickly after disclosure.

The combination of CWE-362 (race condition) and CWE-415 (double free) suggests this is a sophisticated vulnerability that requires deep understanding of Windows kernel internals to exploit. The fact that attackers have already weaponized it tells us we're likely dealing with advanced threat actors who have the resources and expertise to develop kernel exploits.

For defenders, this is a reminder that even with high attack complexity (AC:H in the CVSS score), determined attackers will invest the time to develop reliable exploits for high-value targets. The "high" complexity rating doesn't mean you can deprioritize this—it means the attackers who are using it are skilled and motivated.

Where I Found This Information

Note: This analysis is based on publicly available information from multiple trusted security sources as of November 16, 2025. The situation with actively exploited vulnerabilities can evolve rapidly. Always verify patch compatibility in a test environment before deploying to production systems, but given the active exploitation status, balance testing thoroughness with the urgency of deployment. Stay safe out there, and don't hesitate to reach out to your security community if you need help responding to this threat.

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