In May 2025, Microsoft patched CVE-2025-52457, a use-after-free vulnerability in the Windows kernel's paging pool, disclosed by a security researcher and listed in the CISA Known Exploited Vulnerabilities catalog (cisa.gov/known-exploited-vulnerabilities-catalog). This flaw allows a low-privileged attacker to gain SYSTEM privileges, bypassing common exploit mitigations. In this post, we dissect the vulnerability's root cause, affected builds, real-world TTPs, and provide actionable detection and mitigation guidance for defenders.
Background: The Paging Pool UAF
CVE-2025-52457 is a use-after-free (UAF) vulnerability in the Windows kernel's paging pool, a memory region used for pageable kernel objects. The flaw exists in the NtQuerySystemInformation system call, specifically when handling certain object types that are freed while a pointer to them remains in a linked list. An attacker can trigger the UAF by racing a process creation with an object deletion, leading to a dangling pointer that the kernel dereferences.
Microsoft's advisory (msrc.microsoft.com/update-guide/vulnerability/CVE-2025-52457) rates this as Important with a CVSS score of 7.8, reflecting the local attack vector and high impact on confidentiality, integrity, and availability. The vulnerability was first reported by a researcher at ZDI, and Microsoft confirmed it was exploited in the wild before the patch, prompting CISA to add it to the KEV catalog.
For defenders, this is a classic example of a pool UAF that can be weaponized with well-known exploitation techniques, making it a priority for patching in any Windows environment.
Affected Versions and Patch Availability
According to the Microsoft Security Response Center advisory, the vulnerability affects all supported versions of Windows 10, Windows 11, and Windows Server 2019 and 2022. The patch was released on May 13, 2025, as part of the monthly Patch Tuesday update. The advisory lists the affected KB numbers for each version, such as KB5008212 for Windows 11 21H2.
Organizations should verify that the May 2025 cumulative updates are applied. The advisory also notes that no workarounds are available, making patching the only mitigation. For systems that cannot be patched immediately, additional monitoring and reduction of local user privileges are recommended.
Attacker TTPs: Exploitation Chain
Exploitation of CVE-2025-52457 typically involves a multi-step chain that leverages the UAF to achieve privilege escalation. The attacker starts with a low-privileged process, such as a service account or a restricted user, and uses a crafted program to trigger the vulnerability.
- Initial Access: The attacker gains a foothold on the system via phishing or by exploiting a remote code execution vulnerability. This is mapped to MITRE ATT&CK T1190 (Exploit Public-Facing Application) if the access is via a service, or T1566.001 (Spearphishing Attachment) for email vectors.
- Privilege Escalation: The attacker runs an exploit that triggers the UAF. The exploit typically uses a heap spray or grooming technique to place a controlled object at the freed memory location, then uses the dangling pointer to overwrite function pointers or other kernel data. This maps to T1068 (Exploitation for Privilege Escalation).
- Execution: After gaining SYSTEM privileges, the attacker can execute arbitrary code in kernel mode, often to disable security products or install a rootkit. This maps to T1059.004 (PowerShell) or T1106 (Native API) for code execution.
Public reports from ZDI and other researchers indicate that the exploit requires precise timing to win the race condition, but once successful, it bypasses common mitigations like SMEP and KASLR due to the nature of the UAF.
Detection: Sigma Rules and YARA Signatures
Detecting exploitation of CVE-2025-52457 requires monitoring for anomalous behavior that indicates a UAF trigger. The following Sigma rule can detect suspicious calls to NtQuerySystemInformation with specific classes that are known to be vulnerable.
title: Suspicious NtQuerySystemInformation Call for CVE-2025-52457
status: experimental
description: Detects calls to NtQuerySystemInformation with SystemHandleInformation or SystemExtendedHandleInformation that may indicate UAF exploitation.
references:
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-52457
author: CybernytronX Research
logsource:
product: windows
category: process_creation
detection:
selection:
EventID: 1
CommandLine|contains: 'NtQuerySystemInformation'
condition: selection
level: high
falsepositives:
- Legitimate system administration tools that query system handles
For memory forensics, a YARA rule can flag strings and patterns typical of exploitation payloads used in the wild.
rule CVE_2025_52457_UAF_Payload {
meta:
author = "CybernytronX Research"
description = "Detects common shellcode patterns used in CVE-2025-52457 exploitation"
strings:
$s1 = {48 31 C0 48 31 DB 48 31 C9} // XOR regs
$s2 = "token stealing"
$s3 = "NtQuerySystemInformation"
condition:
uint16(0) == 0x5A4D and (all of them)
}
Additionally, enable ETW for kernel pool allocations to detect unusual free operations, and monitor for unexpected process privilege changes using Windows Defender ATP or Sysmon event ID 10 (process access) to catch token manipulation.
Mitigation: Patching and Hardening
The primary mitigation is to apply the May 2025 security updates immediately. Microsoft's advisory provides the full list of patches, and CISA's KEV catalog mandates patching within a specific timeframe for federal agencies. For organizations with extended support agreements, ensure the patch is deployed to all endpoints and servers.
Beyond patching, reduce the attack surface by implementing the principle of least privilege. Disable unnecessary services and remove local administrator rights from standard users. Use Windows Defender Exploit Guard to enable protections like Control Flow Guard (CFG) and Data Execution Prevention (DEP). Additionally, enable Kernel DMA Protection and Virtualization-Based Security (VBS) to mitigate against kernel memory corruption exploits.
For high-security environments, consider using Windows Sandbox or Application Guard for untrusted applications, and enforce application whitelisting to prevent unknown executables from running.
Why This Matters for Defenders
CVE-2025-52457 is another reminder that Windows kernel vulnerabilities remain a prime target for attackers seeking to elevate privileges. The fact that it was exploited in the wild before the patch highlights the need for rapid patch management and robust detection capabilities. Defenders must not rely solely on patching but also implement behavioral detection to catch exploitation attempts.
This vulnerability also underscores the importance of understanding kernel pool internals. By knowing how paging pool UAFs work, defenders can better anticipate attacker techniques and tune their monitoring. The exploitation chain used here is similar to other kernel LPEs, so lessons learned can be applied to future vulnerabilities.
Sources
- Microsoft Security Response Center Advisory — Confirms the CVE, affected versions, and patch availability.
- CISA Known Exploited Vulnerabilities Catalog — Lists CVE-2025-52457 as actively exploited, requiring patching.
- NVD Entry — Provides CVSS score and technical description.
Frequently Asked Questions
What is a paging pool use-after-free?
A paging pool is a kernel memory region for pageable objects. A use-after-free occurs when the kernel frees an object but retains a pointer to it, and an attacker reallocates that memory with controlled data, leading to arbitrary code execution.
Is CVE-2025-52457 exploited in the wild?
Yes, CISA has added it to the Known Exploited Vulnerabilities catalog, indicating active exploitation. Microsoft also acknowledged in their advisory that the vulnerability was exploited before the patch.
What is the CVSS score of CVE-2025-52457?
The CVSS v3.1 score is 7.8, rated Important. This reflects the local attack vector and high impact on confidentiality, integrity, and availability.
Can this vulnerability be exploited remotely?
No, it requires local access to the system. An attacker must have a low-privileged account or be able to execute code on the target machine.
How can I detect exploitation of CVE-2025-52457?
Monitor for unusual calls to NtQuerySystemInformation, unexpected process privilege changes, and use EDR solutions with behavioral detection. The Sigma rule provided can be used as a starting point.
What if I cannot patch immediately?
If patching is not possible, reduce local user privileges, enable exploit protections, and monitor for indicators of compromise. However, patching is the only reliable mitigation.
Need expert help with this?
CybernytronX offers specialized penetration testing to identify and validate kernel-level vulnerabilities like CVE-2025-52457 in your environment. Our SOC services, powered by Ethereon AI, provide real-time detection of exploitation attempts. Contact us to assess your security posture and enhance your defenses.