CVE-2026-54987 in Windows
Summary
by MITRE • 07/14/2026
Heap-based buffer overflow in Windows Overlay Filter allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 07/14/2026
This vulnerability represents a critical heap-based buffer overflow within the Windows Overlay Filter component that enables local privilege escalation for authenticated attackers. The flaw exists in how the overlay filter handles memory allocation and data processing during file system operations, specifically when managing overlayed file structures. The vulnerability stems from inadequate bounds checking in heap memory management routines where user-supplied data is processed without proper validation, allowing an attacker to overwrite adjacent heap metadata or control data structures.
The technical implementation involves the overlay filter's interaction with the Windows file system filter driver architecture, where malicious input can cause heap corruption that propagates through the kernel memory management subsystem. This type of vulnerability maps directly to CWE-121 Heap-based Buffer Overflow, which is classified under the broader category of memory safety issues in software development practices. The attack vector requires local system access with standard user privileges, but the successful exploitation results in privilege elevation to kernel level execution context.
Operational impact assessment reveals that this vulnerability can be leveraged by attackers who have already established a foothold on a target system through other means such as phishing or social engineering attacks. Once exploited, the attacker gains complete control over the affected Windows system, enabling data exfiltration, persistence mechanisms, and further lateral movement within the network infrastructure. The vulnerability affects multiple Windows versions including windows 10, windows server 2016, and windows server 2019, making it particularly concerning for enterprise environments where these operating systems are prevalent.
The exploitation process typically involves crafting specific file operations that trigger the vulnerable code path, manipulating heap allocation patterns to achieve controlled overwrite of critical kernel structures, and subsequently executing arbitrary code with system-level privileges. Mitigation strategies include applying Microsoft security patches immediately upon release, implementing application whitelisting policies to restrict potentially malicious file operations, and monitoring for anomalous heap memory behavior through endpoint detection and response solutions. Additionally, organizations should consider implementing the principle of least privilege and regular security assessments to identify potential exploitation vectors before they can be effectively weaponized by threat actors.
From an adversarial perspective, this vulnerability aligns with tactics described in the attack framework under technique T1068 Privilege Escalation and T1543 Create or Modify System Process. The vulnerability represents a classic case where insufficient input validation in kernel-mode components creates opportunities for attackers to bypass security controls and establish persistent access to target systems. Security teams should prioritize immediate patch deployment while maintaining vigilance for indicators of compromise related to unauthorized privilege escalation attempts within their monitored environments, particularly focusing on unusual file system filter activities or unexpected process creation patterns that may indicate exploitation attempts.