CVE-2025-24991 (Microsoft Windows NTFS Out-Of-Bounds Read)

What this CVE means in practice

CVE-2025-24991 is an out-of-bounds read in Microsoft Windows NTFS, so the core issue is not just that a file system parser can fail, but that crafted local interaction can cause it to read past intended memory boundaries and disclose information.

That matters because file systems sit on a high-trust path between storage media, the OS kernel, and many user workflows. Even when the immediate effect is information disclosure rather than direct code execution, a memory-safety flaw in NTFS can expose data that should have remained hidden, including fragments of process memory or other sensitive state.

For canonical vulnerability detail and record status, use the CVE Program and the NIST National Vulnerability Database rather than relying on secondary summaries.

Why NTFS out-of-bounds reads are dangerous

NTFS is deeply embedded in Windows storage handling, so parser weaknesses can be reachable through ordinary file access paths, removable media, archives, or other local workflows that cause the operating system to inspect attacker-influenced data.

An out-of-bounds read can leak information that helps attackers in later stages, such as memory layout details, security-relevant strings, or other content that should not have been exposed. In practice, disclosure bugs often become force multipliers because they reduce uncertainty for follow-on exploitation.

Because this is a Windows file system issue, the security consequence is often less about a single isolated read and more about what that read reveals inside a broader endpoint compromise path, especially when attackers already have local execution or a foothold.

How organisations check exposure and reduce attack surface

Exposure review starts with identifying Windows endpoints, servers, and virtual machines that rely on NTFS, then checking whether they can ingest untrusted files from users, shared locations, mounted media, or external sources. Internet-facing exposure is usually indirect here, but local and post-access exposure can still be significant.

Teams should compare asset inventory against vendor advisories and the CISA KEV catalogue, then prioritise systems that are both reachable and business-critical. For vulnerability triage and remediation workflow design, the Vulnerability Management Guide is a practical companion for asset scoping, KEV prioritisation, and verification.

Where patching is delayed, compensating controls usually focus on limiting who can introduce or open untrusted content, reducing local admin sprawl, hardening endpoint monitoring, and narrowing the paths by which malicious files can reach affected systems.

Detection, remediation, and compromise review

After remediation, organisations should still review whether exploitation may already have occurred, because CVEs in the KEV catalogue are known to be used in real attacks. That review should include unusual file access, unexpected crashes, kernel or storage-related telemetry, and any signs that sensitive information may have been exposed before the fix.

When a file-system vulnerability is involved, post-patch review should not stop at patch status. It should also ask whether the disclosed information could have enabled later access, session theft, or privilege escalation elsewhere in the environment.

For practical remediation patterns around memory-safety flaws and exploited CVEs, the CWE Top 25 Guide helps frame the weakness class, while the State of NHI & AI Agent Breach Report 2026 illustrates how seemingly narrow disclosures can become part of larger intrusion chains.

Risk and Threat Considerations

Because CISA placed this CVE in KEV, the main risk is not hypothetical exposure, but exposure that has already been demonstrated in the wild. For NTFS flaws, that raises the likelihood that attackers will use local access or a prior foothold to extract information that supports follow-on compromise.

Failure mechanism: An attacker or malicious file causes NTFS to read beyond intended bounds, then leverages the resulting information disclosure to reduce uncertainty about memory, data structures, or security state.

Impact: The leak can assist privilege escalation, session abuse, or deeper endpoint compromise when paired with other weaknesses or an existing local foothold.

Practitioner Guidance

Why practitioners should care: Treat this as a memory-safety and exposure problem, not just a patch ticket. A local NTFS disclosure bug can matter most on systems where users routinely open untrusted content or where local access is already contested.

What to watch for: Prioritise systems that are both in the KEV window and operationally exposed to untrusted local file handling, then validate that patching, scanning, and incident review all cover the same asset set.

Practitioner takeaway: For exploited file-system CVEs, remediation must be paired with exposure review, because the security question is not only whether the bug is fixed, but whether anything useful was leaked before it was.

Related resources from NHI Mgmt Group

• CVE-2023-36424 (Microsoft Windows Out-of-Bounds Read)
• CVE-2013-3918 (Microsoft Windows Out-of-Bounds Write)
• CVE-2025-5777 (Citrix NetScaler ADC and Gateway Out-of-Bounds Read)
• CVE-2025-5419 (Google Chromium V8 Out-of-Bounds Read and Write)