CVE-2025-21180 in Windows
Summary
by MITRE • 03/11/2025
Heap-based buffer overflow in Windows exFAT File System allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 07/02/2025
The vulnerability identified as CVE-2025-21180 represents a critical heap-based buffer overflow within the Windows exFAT file system implementation that presents a significant security risk to affected systems. This flaw exists in the way the operating system handles exFAT file system operations, specifically when processing malformed or specially crafted exFAT volumes that trigger memory corruption during file system parsing. The vulnerability stems from insufficient input validation and bounds checking within the exFAT driver components, which fail to properly validate the size and structure of data elements during file system operations. When an attacker can manipulate the exFAT file system structures, particularly through crafted file names, directory entries, or volume metadata, the system becomes susceptible to memory corruption that can be exploited to execute arbitrary code with the privileges of the affected process.
The technical exploitation of this vulnerability occurs through a heap-based buffer overflow condition that allows attackers to overwrite adjacent memory locations within the exFAT file system driver's heap allocation regions. This type of vulnerability falls under the CWE-121 heap-based buffer overflow category, where insufficient bounds checking on heap-allocated memory regions enables attackers to overwrite critical data structures, function pointers, or return addresses. The attack vector requires local execution privileges since the vulnerability manifests during normal file system operations on exFAT volumes, making it accessible to any user with the ability to interact with exFAT formatted storage devices. The flaw is particularly concerning because it can be triggered through legitimate file system operations such as mounting exFAT volumes, reading directory structures, or accessing specific file attributes that cause the vulnerable code paths to execute.
The operational impact of CVE-2025-21180 extends beyond simple local privilege escalation to potentially enable full system compromise when combined with other attack vectors or when executed in specific environments where attackers can leverage the privilege escalation to gain SYSTEM-level access. The vulnerability affects all Windows versions that support exFAT file systems including Windows 10, Windows 11, and various Windows Server editions, making it a widespread concern across enterprise and consumer environments. Attackers can exploit this vulnerability by creating specially crafted exFAT volumes that contain malformed data structures, which when mounted or accessed by a victim system trigger the buffer overflow condition. This type of attack aligns with the ATT&CK technique T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation, potentially allowing attackers to establish persistent access or escalate privileges to SYSTEM level.
Mitigation strategies for this vulnerability should focus on immediate patching of affected systems through Microsoft's regular security updates, as well as implementing administrative controls to restrict exFAT volume mounting from untrusted sources. Organizations should consider disabling automatic mounting of exFAT volumes from removable media or network shares until patches are deployed, and implementing network monitoring to detect suspicious file system access patterns. The vulnerability demonstrates the importance of robust input validation and memory safety practices in operating system components, particularly in file system drivers that handle untrusted data from external storage devices. System administrators should also consider implementing endpoint protection solutions that can detect and block suspicious file system access patterns that may indicate exploitation attempts, while maintaining comprehensive logging of file system operations to aid in incident response efforts. Additionally, organizations should conduct vulnerability assessments to identify systems running affected Windows versions and prioritize patch deployment based on risk exposure and business criticality.