Description

Use after free in Windows DNS allows an unauthorized attacker to elevate privileges over a network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.1",
  "pubDate": "2026-08-11T17:18:30.990Z",
  "pubdate": "2026-08-11T17:18:30.990Z",
  "executiveSummary": "This vulnerability is classified as a Use-After-Free (UAF) memory corruption flaw affecting the Windows DNS service. Successful exploitation of this vulnerability allows an unauthorized remote attacker to execute arbitrary code within the context of a privileged security context, leading to a complete elevation of privileges over a network. The primary affected system is the Windows DNS server component, which handles incoming domain name system queries and responses.\nThe risk implications are severe, as an unauthenticated threat actor can leverage network-based access vectors to compromise the underlying operating system kernel or critical service boundaries. The attack capabilities include remote code execution, systemic instability, and unauthorized access to sensitive system resources. Exploitation requirements rely on the attacker's ability to interact with the vulnerable Windows DNS service over the network, triggering memory management flaws during object allocation and deallocation cycles. Given the widespread deployment of the Windows DNS service in enterprise environments, remediation is critical to prevent domain-wide compromise and lateral movement by malicious entities.",
  "technicalDetails": "The root cause of the vulnerability resides in improper memory management within the Windows DNS service when processing specific malformed DNS queries or packets. Specifically, a Use-After-Free condition occurs when a memory object is prematurely freed or deallocated while internal pointers still reference the memory address. If an attacker can manipulate heap allocations prior to the dangling pointer being dereferenced, they can achieve arbitrary memory read and write primitives.\nThe vulnerable component is the packet processing and state management subsystem of the Windows DNS service. The attack vector is network-exposed, requiring no prior authentication or local privilege requirements, meaning an unauthorized remote attacker can initiate the exploit stream directly over the network protocol stack. The attack flow begins when the attacker transmits a crafted sequence of DNS packets designed to manipulate object lifecycles within the heap.\nDuring the exploitation sequence, the DNS service allocates memory for a specific request structure, processes an initial operation, and prematurely releases the allocated buffer back to the heap manager while maintaining a reference to the freed memory. The attacker then sends a series of subsequent allocation requests, often referred to as heap spraying or grooming, to occupy the newly freed memory chunk with controlled payload data. When the Windows DNS service subsequently attempts to access the dangling pointer, it interacts with the attacker-controlled data instead of the legitimate structure.\nThis erroneous dereference redirects execution flow to attacker-specified instructions or manipulates critical function pointers. The payload behavior facilitates remote code execution within a highly privileged context, such as SYSTEM or Network Service depending on the service configuration. The post-exploitation impact includes full system compromise, persistent backdoor installation, and the ability to pivot further into the internal network infrastructure."
}