Is CVE-2025-24991 (Microsoft Windows NTFS Out-Of-Bounds Read) being exploited in the wild?

How to confirm active exploitation for CVE-2025-24991

The practical question is not whether the flaw exists, but whether exposure is still current in your environment. Start by identifying every Windows asset that uses NTFS, then verify whether it is covered by your vulnerability management process and whether it appears in the CISA Known Exploited Vulnerabilities Catalog and the NIST National Vulnerability Database record for the CVE. For a question framed around "in the wild" exploitation, KEV inclusion is the strongest operational signal that the issue has moved from theoretical to actionable.

Because the direct answer already establishes that the vulnerability allows local information disclosure through an out-of-bounds read, the key exposure test is whether any affected system is reachable by an authorized local user or local code execution path. That makes endpoint coverage, local logon pathways, and administrative access paths relevant to triage.

When you need a playbook for this kind of triage, use the Zero-Day and Exploited Vulnerabilities Guide to structure verification, KEV-driven prioritisation, emergency mitigation, and post-patch hunting around the exact question of active exploitation.

Why an NTFS out-of-bounds read matters operationally

An out-of-bounds read is often treated as a lower-severity memory-safety issue than code execution, but it still matters when the leaked data can help an attacker map memory, disclose sensitive information, or support a follow-on exploit chain. In this case, the issue is local and authorized, so the security question is less about remote intrusion and more about whether local access on a sensitive system can expose information that should remain hidden.

That distinction is important for incident responders. If the flaw is abused on a workstation, server, or privileged jump host, the likely consequence is information disclosure rather than immediate takeover. But disclosure can still matter when the target stores credentials, tokens, session material, forensic evidence, or other data that improves the next stage of an attack.

The most useful way to think about it is as a trust-boundary failure inside the file system stack. A flaw in a core storage component can be hard to spot from ordinary endpoint telemetry, so the absence of obvious malware does not prove the system was not touched.

What to do if you cannot patch immediately

If patching is delayed, prioritize exposure reduction around the systems that matter most, not just the ones that are easiest to reach. Restrict local interactive access, remove unnecessary administrative logon rights, and treat any system that processes sensitive data as higher priority than a general-purpose desktop.

For defenders, the right short-term move is to narrow who can exercise the local access condition that the vulnerability requires. That does not remove the flaw, but it can reduce the number of actors who could realistically trigger it before remediation is available.

Use the FIRST EPSS score only as a prioritisation aid, not as proof of compromise. Combine it with KEV status, asset criticality, and whether the system exposes data whose disclosure would matter if local memory were read.

Risk and Threat Considerations

This vulnerability is significant because it sits in a foundational Windows file system component and is already treated as actively exploited by CISA. Even when exploitation is local, attackers can use such flaws after gaining a foothold, or abuse them on shared systems where local access is easier to obtain than full administrative control.

Failure mechanism: An out-of-bounds read can reveal memory that should not be visible to the caller, which can expose sensitive information or help an attacker shape follow-on activity.

Impact: The immediate impact is information disclosure, but the practical risk is broader if the leaked data helps with privilege escalation, persistence, or lateral movement elsewhere in the environment.

Practitioner Guidance

What to verify: Confirm whether every Windows system that uses NTFS is in scope for patching or mitigation, then check whether any high-value host was accessed by a local user or suspicious process during the exposure window. If you cannot validate the patch state, treat the asset as still at risk.

What to measure: Track time-to-remediate from KEV publication, and separate routine patch latency from emergency response latency. For exploited vulnerabilities, the important metric is not how many systems are eventually patched, but how quickly the highest-value hosts are removed from exposure.

Practitioner takeaway: For a KEV-listed flaw, assume exploitation is a live operational concern until you have both patch confirmation and enough telemetry to rule out local abuse on the systems that matter most.

Related resources from NHI Mgmt Group

• CVE-2025-24991 (Microsoft Windows NTFS Out-Of-Bounds Read)
• Is CVE-2023-36424 (Microsoft Windows Out-of-Bounds Read) being exploited in the wild?
• Is CVE-2013-3918 (Microsoft Windows Out-of-Bounds Write) being exploited in the wild?
• Is CVE-2025-5777 (Citrix NetScaler ADC and Gateway Out-of-Bounds Read) being exploited in the wild?