Description

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

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.8",
  "pubDate": "2026-08-11T17:18:34.327Z",
  "pubdate": "2026-08-11T17:18:34.327Z",
  "executiveSummary": "This vulnerability is a heap-based buffer overflow affecting the Windows SMB Server component. The flaw enables an authorized remote attacker to execute arbitrary code with elevated privileges over the network.\nThe affected system is Windows SMB Server. The primary risk implication is complete system compromise, as successful exploitation allows remote code execution within the context of the affected service or underlying operating system.\nAttacker capabilities include network-based interaction with the targeted SMB Server instance. Exploitation requirements necessitate that the attacker possesses authorization to access the SMB service, allowing them to interact with vulnerable memory allocation routines during protocol transaction processing.",
  "technicalDetails": "The root cause of the vulnerability is a heap-based buffer overflow within the Windows SMB Server component. This memory corruption flaw typically arises from improper bounds checking or arithmetic overflow during the parsing and handling of specially crafted SMB packets or transactional data structures allocated on the heap.\nThe vulnerable component is the Windows SMB Server protocol handler responsible for managing incoming client requests and allocating dynamic memory buffers to process packet payloads.\nNetwork exposure is present via the Server Message Block protocol, typically operating over TCP ports 445 or 139, allowing remote connectivity from clients with network routing capabilities to the target host.\nAuthentication requirements specify that the attacker must be an authorized user to interact with the SMB Server, implying that valid credentials or an established authenticated session are prerequisites for initiating the malicious transaction flow.\nPrivilege requirements depend on the execution context of the vulnerable service, frequently granting high-privilege code execution upon successful exploitation due to the privileged nature of kernel-mode or high-integrity user-mode SMB server components.\nThe attack flow proceeds as follows: First, the authorized attacker establishes a network connection to the target Windows SMB Server. Second, the attacker transmits a specially crafted SMB packet designed to trigger improper memory allocation sizes or bypass bounds validation checks. Third, the SMB Server parses the malicious payload, leading to a heap-based buffer overflow as data is written beyond the boundaries of the allocated heap chunk. Fourth, adjacent heap metadata or critical function pointers are overwritten with attacker-controlled data.\nPayload behavior involves hijacking the control flow of the application by redirecting execution pointers to shellcode or utilizing Return-Oriented Programming (ROP) chains residing in memory.\nPost-exploitation impact includes arbitrary code execution, lateral movement across the network, installation of persistent backdoors, and total compromise of the affected host operating system."
}