Description

Heap-based buffer overflow in Microsoft Exchange Server allows an authorized attacker to execute code over a network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.8",
  "pubDate": "2026-08-11T17:18:45.323Z",
  "pubdate": "2026-08-11T17:18:45.323Z",
  "executiveSummary": "This vulnerability is classified as a heap-based buffer overflow affecting Microsoft Exchange Server. The primary impact of successful exploitation is arbitrary code execution over the network, allowing an authenticated attacker to compromise the underlying host system.\nThe affected product is Microsoft Exchange Server. The risk implications are severe, as compromise of an enterprise mail server typically grants the adversary extensive access to internal communications, directory services, and potentially credentials or elevated network privileges.\nRegarding attacker capabilities and requirements, the threat actor must possess network access to the target Exchange Server and hold authorized credentials within the environment. Exploitation hinges on memory corruption primitives occurring during data processing within the vulnerable heap implementation, ultimately leading to control flow hijacking and malicious payload execution.",
  "technicalDetails": "The root cause of the vulnerability stems from improper bounds checking during memory allocation and management within the heap-based data structures of Microsoft Exchange Server. When specific input data is processed over the network by the vulnerable component, the application fails to adequately validate the size of the incoming data relative to the allocated heap buffer size.\nExploitation occurs when an authorized attacker interacts with the network services exposed by Microsoft Exchange Server, transmitting a specially crafted payload designed to exceed the boundaries of the targeted heap buffer. As the input is processed, the surplus data overwrites adjacent memory regions on the heap, corrupting critical metadata, function pointers, or object structures managed by the memory allocator.\nThe attack flow proceeds as follows: First, the authenticated attacker initiates a network connection to the vulnerable service on the Microsoft Exchange Server. Second, the attacker transmits the malicious request containing oversized data designed to trigger the heap-based buffer overflow. Third, the internal memory management routine writes the incoming stream beyond the intended buffer limits. Finally, by carefully engineering the layout of the heap and the overwritten contents, the attacker achieves arbitrary code execution within the security context of the Exchange service process.\nThe vulnerability involves network exposure, as the attack vector relies on remote network protocols interacting with the server. Privilege and authentication requirements mandate that the attacker must be authorized, meaning anonymous access is insufficient; the adversary must operate with valid credentials. The post-exploitation impact includes full system compromise, lateral movement within the enterprise network, data exfiltration, and persistence capabilities due to the high privileges typically associated with Microsoft Exchange Server processes."
}