CVE-2026-49172 in Windows
Summary
by MITRE • 07/14/2026
Heap-based buffer overflow in Windows FTP Service allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 07/15/2026
A heap-based buffer overflow vulnerability exists within the Windows FTP service implementation that enables remote code execution by unauthenticated attackers. This critical flaw resides in the service's handling of malformed data structures during network communication, specifically when processing user input through the ftpd.exe process. The vulnerability manifests when the service fails to properly validate buffer boundaries during memory allocation operations, allowing attackers to overwrite adjacent heap memory regions with malicious payloads.
The technical exploitation occurs through carefully crafted FTP commands that trigger memory corruption in the heap management subsystem. When the FTP service processes oversized or malformed command arguments, it allocates insufficient memory buffers while still attempting to copy user-supplied data beyond allocated boundaries. This memory corruption can be leveraged to manipulate function pointers, return addresses, or other critical control structures within the process memory space. The vulnerability operates at the heap level rather than stack-based exploitation, making it more difficult to detect and prevent through traditional stack protection mechanisms such as stack canaries.
From an operational perspective, this vulnerability presents a severe threat to Windows server environments that have FTP services enabled, particularly those exposed to untrusted networks or internet-facing systems. Attackers can exploit this weakness without authentication requirements, potentially gaining full system control over affected servers. The impact extends beyond simple remote code execution to include privilege escalation opportunities, data exfiltration capabilities, and potential lateral movement within compromised network environments. Organizations with default Windows installations that maintain FTP service functionality are particularly at risk since this vulnerability affects the core ftpd.exe service binary.
The exploitation pattern aligns with attack techniques documented in the mitre ATT&CK framework under T1210 for exploitation of remote services and T1059 for command execution. This vulnerability is classified as a CWE-121 heap-based buffer overflow where insufficient bounds checking permits memory corruption through improper handling of dynamic memory allocation. Security practitioners should note that Windows FTP service implementations have historically been targeted in various exploit campaigns, making this vulnerability particularly dangerous in environments lacking proper network segmentation or intrusion detection measures.
Mitigation strategies should prioritize immediate patching of affected Windows systems through Microsoft security updates, followed by disabling unnecessary FTP services and implementing network-level restrictions. Network administrators should consider deploying IDS/IPS signatures specific to known exploitation patterns, while also implementing host-based security controls such as application whitelisting and memory protection features. Additional defensive measures include monitoring for unusual FTP traffic patterns, restricting FTP service access to trusted IP ranges, and maintaining regular vulnerability assessments targeting Windows server environments. Organizations should also ensure comprehensive incident response procedures are in place to address potential exploitation attempts.