CVE-2026-62790 in Windows
Summary
by MITRE • 08/11/2026
Heap-based buffer overflow in Windows SMB Server allows an authorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability represents a critical heap-based buffer overflow flaw within the Windows Server Message Block protocol implementation that enables remote code execution when exploited by authenticated attackers. The vulnerability resides in the SMB server component responsible for handling network file sharing operations and is classified under CWE-122 as heap-based buffer overflow, where insufficient bounds checking allows malicious data to overwrite adjacent heap memory regions. The flaw manifests when the SMB server processes specially crafted packets containing oversized data structures that exceed allocated buffer boundaries, potentially allowing attackers to overwrite critical memory pointers or code segments.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with the capability to execute arbitrary code within the context of the SMB service account, which typically runs with high privileges on Windows systems. Attackers can leverage this vulnerability by establishing authenticated connections to target systems and sending malicious SMB packets that trigger the buffer overflow condition during packet processing. The attack vector requires network connectivity and valid credentials or a way to obtain them through credential harvesting techniques, making it particularly dangerous in enterprise environments where SMB is widely used for file sharing and network communication. This vulnerability aligns with ATT&CK technique T1075 which covers legitimate credentials use and T1210 which covers exploitation of remote services.
The technical nature of this heap overflow allows for various exploitation methods including stack pivoting, return-oriented programming, or direct code execution within the vulnerable process memory space. The Windows SMB server implementation lacks proper input validation mechanisms that would detect oversized buffer operations before memory allocation occurs, creating a window where malicious data can be processed and cause memory corruption. This vulnerability is particularly concerning because it operates at the protocol level where attackers can leverage legitimate network services to maintain persistence and move laterally within networks. Organizations must understand that exploitation of this vulnerability could lead to complete system compromise and unauthorized access to sensitive network resources.
Mitigation strategies should include immediate deployment of Microsoft security patches addressing the specific SMB buffer overflow vulnerability, along with network segmentation to limit SMB service exposure, implementation of network monitoring solutions to detect anomalous SMB traffic patterns, and strict access controls limiting who can authenticate to SMB services. Organizations should also consider disabling SMBv1 protocol entirely as it represents a legacy protocol with known security weaknesses, while implementing robust endpoint detection and response capabilities to identify potential exploitation attempts. Additionally, regular security assessments should verify that all Windows systems have proper patch management procedures in place to prevent similar vulnerabilities from being exploited in the future, considering that this vulnerability type falls under common attack patterns documented in various threat intelligence feeds and security advisories.