CVE-2026-57091
Summary
by MITRE • 07/14/2026
Stack-based buffer overflow in Windows File History Service allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 07/14/2026
A stack-based buffer overflow vulnerability exists within the Windows File History Service component that enables an authenticated local attacker to achieve privilege escalation. This flaw resides in the service's handling of input data structures during file synchronization operations, where insufficient bounds checking permits arbitrary data to overwrite adjacent memory locations on the stack. The vulnerability specifically manifests when the service processes malformed or excessively long input parameters through its internal processing routines, creating a condition where attacker-controlled data can overwrite return addresses and execution pointers stored in the call stack.
The technical implementation of this vulnerability follows a classic stack-based buffer overflow pattern where a fixed-size buffer receives more data than allocated space, typically through user-supplied inputs or manipulated service parameters. The File History Service operates with elevated privileges to perform file system operations, making this local privilege escalation vector particularly dangerous as it allows an attacker who has already established a foothold on the system to gain SYSTEM-level access. The vulnerability's exploitation requires local authentication since the service runs under privileged contexts and the attack surface is limited to processes that can interact with the File History Service API.
From an operational perspective, this vulnerability represents a significant risk in enterprise environments where multiple users may have local access to systems running Windows with File History enabled. The attack scenario typically involves an attacker first gaining standard user credentials through social engineering, credential theft, or other initial compromise techniques, then leveraging this local access to execute the buffer overflow exploit against the File History Service. The successful exploitation results in arbitrary code execution with SYSTEM privileges, enabling the attacker to bypass traditional security controls, access sensitive data, modify system configurations, and establish persistent access to the compromised system.
Organizations should implement immediate mitigations including applying Microsoft's security patches addressing this vulnerability, disabling the File History service if not required for operations, and implementing additional local privilege monitoring controls. The vulnerability aligns with CWE-121 Stack-based Buffer Overflow and maps to ATT&CK technique T1068, Local Privilege Escalation, while also potentially correlating with T1547.001 Account Manipulation and T1059 Command and Scripting Interpreter techniques. Security teams should monitor for suspicious process creation patterns involving the File History service executable and implement behavioral analytics to detect anomalous stack manipulation activities that may indicate exploitation attempts. Additionally, mandatory access controls and privilege separation measures should be enforced to limit potential damage from successful exploitation attempts, particularly in environments where the File History service remains enabled for legitimate backup operations.