Description

Heap-based buffer overflow in Windows iSCSI Target Service allows an unauthorized attacker to execute code over a network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.1",
  "pubDate": "2026-08-11T17:18:55.703Z",
  "pubdate": "2026-08-11T17:18:55.703Z",
  "executiveSummary": "A heap-based buffer overflow vulnerability exists within the Windows iSCSI Target Service, representing a critical security flaw in the network storage architecture of affected operating systems. This vulnerability enables an unauthorized remote attacker to achieve arbitrary code execution over the network without requiring prior authentication or user interaction.\nThe flaw resides in how the iSCSI Target Service parses incoming network data and manages dynamic memory allocations within the heap. Improper boundary checks during packet processing allow malicious payloads to overwrite adjacent memory structures, corrupting critical function pointers or heap metadata.\nSuccessful exploitation of this vulnerability poses severe risk implications, potentially leading to a complete system compromise. An adversary who successfully exploits this flaw gains the ability to execute arbitrary code with the high privileges associated with the service, which typically runs under a privileged system context.\nThe attack vector is network-based, meaning any system exposing the vulnerable iSCSI Target Service to an untrusted network or the internet is at immediate risk. Exploitation requirements are minimal due to the lack of authentication constraints, allowing unauthenticated attackers to interact directly with the listening service and trigger the memory corruption condition.",
  "technicalDetails": "The vulnerability is a classic heap-based buffer overflow stemming from inadequate input validation and missing bounds checks within the Windows iSCSI Target Service component. The vulnerable component is responsible for handling incoming iSCSI protocol communications, specifically managing session establishment, command parsing, and data transfer operations over network sockets.\nThe root cause lies in the improper calculation of buffer sizes when allocating memory on the heap to store incoming network requests or protocol data units (PDUs). When the iSCSI Target Service processes a specially crafted packet containing an oversized payload, the amount of data written to the heap destination buffer exceeds the allocated memory chunk boundary. This results in an out-of-bounds write condition that overwrites adjacent heap chunks, control structures, or object vftables.\nExploitation occurs through a step-by-step network-based attack flow. First, an unauthenticated attacker establishes a network connection to the target system on the port utilized by the Windows iSCSI Target Service. Second, the attacker transmits a malformed iSCSI PDU designed to trigger the vulnerable code path during memory allocation and data copying routines. Third, as the service parses the malicious input, the heap buffer overflow is triggered, allowing the attacker to corrupt adjacent memory allocations with controlled data.\nBy carefully engineering the payload, the attacker can manipulate the overwritten heap metadata or function pointers to hijack control flow when the corrupted objects are subsequently referenced or freed. This facilitates arbitrary code execution within the context of the service. Given that the Windows iSCSI Target Service typically operates with elevated system privileges, successful execution of shellcode or malicious binaries results in immediate local privilege escalation and complete compromise of the underlying operating system.\nThe attack requires no authentication or user interaction, exposing network-accessible instances to remote exploitation. The vulnerability affects the Windows iSCSI Target Service across vulnerable product versions as specified by official vendor advisories."
}