CVE-2026-71336 in Windows
Summary
by MITRE • 09/09/2026
Integer overflow or wraparound in Windows Work Folder Service allows an authorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified involves a critical integer overflow condition within the Microsoft Windows Work Folders service, specifically affecting components responsible for handling file synchronization and management operations. This flaw arises when the application fails to properly validate arithmetic operations involving user-supplied or system-generated data structures related to folder metadata or file size calculations. When an attacker crafts specific requests that trigger this miscalculation, the resulting integer value wraps around due to insufficient bounds checking, leading to incorrect memory allocation sizes or buffer length determinations. This type of error is a classic example of CWE-190 Integer Overflow or Wraparound, where the computational result exceeds the maximum limit for the data type used by the system, causing it to reset to a small positive number rather than throwing an exception or handling the overflow gracefully.
The operational impact of this vulnerability is severe because it allows for remote code execution without requiring local user interaction beyond network connectivity. Since the Windows Work Folders service listens on specific ports and processes incoming synchronization requests from authorized clients, an attacker who possesses valid credentials can exploit this flaw over a standard network connection. By sending specially crafted packets that trigger the integer overflow during the processing of file metadata or directory structures, the attacker can cause a buffer overrun in adjacent memory regions. This corruption allows for arbitrary code execution with the privileges of the service account running the Work Folders process, which typically holds significant permissions to manage user data and system resources.
This attack vector aligns closely with MITRE ATT&CK techniques related to remote exploitation via network services, particularly those involving application layer protocols where input validation is insufficient. The ability to execute code remotely through a legitimate administrative service makes this vulnerability highly dangerous in enterprise environments where Work Folders are deployed for mobile device management and data synchronization. Attackers can leverage this access to establish persistence, escalate privileges further by targeting other local vulnerabilities, or move laterally across the network using stolen credentials obtained from the compromised system memory.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The primary defense is applying the latest security patches released by Microsoft that address the input validation logic within the Work Folders service components. Organizations should prioritize patching systems where this role is enabled, especially those exposed to untrusted networks or having remote access capabilities. Additionally, implementing network segmentation to restrict access to the specific ports used by Windows Work Folders can limit the attack surface for potential exploit attempts. Security teams should also monitor for anomalous behavior in file synchronization logs and enforce strict least-privilege principles for service accounts associated with these services to minimize the impact if a compromise occurs. Regular vulnerability assessments and penetration testing focused on network-facing services are essential to identify similar implementation flaws before they can be exploited by malicious actors.