Description

Heap-based buffer overflow in Windows HTTP Print Provider allows an unauthorized attacker to execute code over a network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-09-08T18:19:48.147Z",
  "pubdate": "2026-09-08T18:19:48.147Z",
  "executiveSummary": "A critical heap-based buffer overflow vulnerability has been identified within the Windows HTTP Print Provider component, a subsystem responsible for handling remote print jobs and print-related communications over HTTP/HTTPS protocols.\nThis security flaw presents an extreme risk to enterprise environments, as it allows an unauthenticated, remote attacker to execute arbitrary code with elevated system privileges on the target host.\nBecause the exploitation can be initiated over the network without requiring any user interaction or prior authentication, the vulnerability poses a severe threat of remote system compromise and lateral propagation.\nSystems exposing Windows print services to external or untrusted networks are particularly vulnerable, necessitating immediate mitigation and remediation efforts to prevent unauthorized access and exploitation.",
  "technicalDetails": "The root cause of this vulnerability lies in the Windows HTTP Print Provider, which fails to properly validate the length of incoming data before copying it into an allocated buffer on the heap. When processing print requests transmitted via HTTP or HTTPS, the component dynamically allocates memory to store incoming packet headers, printer configuration parameters, or print job metadata. Due to insufficient bounds checking on these input fields, a remote attacker can transmit a payload that exceeds the pre-allocated memory space. This action leads to a heap-based buffer overflow, where excess data overflows the boundary of the designated heap chunk and overwrites adjacent memory blocks, including critical control structures or function pointers used by the process.\nAn attacker initiates the exploit flow by targeting the network port hosting the Windows HTTP Print Provider service. The attacker generates a highly structured, malicious HTTP request containing specifically malformed headers or body content designed to trigger the vulnerable memory allocation routine. Since the service does not require authentication for initial print provider negotiations, the unauthorized packet is accepted and processed by the system. Once the payload is parsed, the boundary violation occurs. By carefully constructing the overflowing data, the attacker can overwrite adjacent heap metadata, such as chunk headers (including forward and backward pointers in a doubly-linked list of free memory blocks), or target active object vtables. When the system subsequently attempts to free the corrupted memory chunk or references a modified virtual function pointer, execution flow is redirected to the attacker-controlled shellcode residing within the overwritten buffer.\nThe payload typically executes within the security context of the service hosting the HTTP Print Provider, which often runs with high privileges such as NT AUTHORITY\\SYSTEM. Successful exploitation bypasses standard operating system memory protections, leading to remote code execution (RCE). The immediate post-exploitation impact includes the deployment of interactive shells, creation of unauthorized administrative accounts, installation of persistent backdoors, or the execution of arbitrary commands. Because the vulnerability is reachable over the network without authentication, the attack vector represents a significant threat to internal print servers and any internet-facing hosts exposing print endpoints, allowing complete compromise of the underlying operating system and logical network segment."
}