CVE-2026-62913 in Exchange Server
Summary
by MITRE • 08/11/2026
Heap-based buffer overflow in Microsoft Exchange Server allows an authorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 08/12/2026
A heap-based buffer overflow vulnerability exists within Microsoft Exchange Server that enables authenticated attackers to execute arbitrary code remotely over the network. This critical security flaw resides in the server's memory management mechanisms where insufficient bounds checking permits data to overflow allocated heap memory regions. The vulnerability manifests when legitimate user credentials are leveraged to send specially crafted requests that trigger the buffer overflow condition, allowing an attacker with valid authentication to escalate privileges and gain remote code execution capabilities. Such a vulnerability directly violates the principle of least privilege and undermines the integrity of the Exchange server's security model.
The technical implementation of this flaw involves improper input validation within Exchange Server's processing routines where heap memory allocations do not adequately verify the size of incoming data payloads. When an authenticated user submits malicious input through standard Exchange protocols or web services, the system fails to properly constrain buffer boundaries, resulting in memory corruption that can be exploited to overwrite critical memory locations including return addresses and function pointers. This type of vulnerability maps directly to CWE-121 heap-based buffer overflow classification and represents a serious deviation from secure coding practices outlined in the OWASP Secure Coding Standards.
The operational impact of this vulnerability extends beyond simple code execution as it provides attackers with persistent access to corporate email infrastructure that often serves as a critical communication hub for business operations. Once exploited, the attacker can leverage the compromised Exchange server to conduct lateral movement within network environments, harvest sensitive email communications, access calendar data, and potentially establish persistence mechanisms through legitimate administrative accounts. The attack surface is particularly concerning given that Exchange servers frequently operate with elevated privileges and maintain access to critical organizational data repositories.
Mitigation strategies should prioritize immediate deployment of Microsoft security patches and updates while implementing network segmentation controls to limit lateral movement opportunities. Organizations must enforce strict authentication policies including multi-factor authentication, implement monitoring solutions to detect anomalous behavior patterns, and establish robust incident response procedures for rapid containment of potential exploitation attempts. Security teams should also consider deploying web application firewalls and network-based intrusion detection systems to identify and block malicious traffic patterns associated with this vulnerability class. The ATT&CK framework categorizes such exploits under the T1059 execution techniques, emphasizing the need for comprehensive endpoint protection and behavioral analysis capabilities to detect and prevent unauthorized code execution activities.