Description

Integer overflow or wraparound in Windows DNS allows an authorized attacker to elevate privileges locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.7",
  "pubDate": "2026-08-11T17:19:00.113Z",
  "pubdate": "2026-08-11T17:19:00.113Z",
  "executiveSummary": "An integer overflow or wraparound vulnerability has been identified within Windows DNS, which can be exploited by an authorized threat actor to achieve local privilege escalation.\nThe vulnerability resides in the core processing logic of the Windows DNS component, where improper handling of integer boundaries during arithmetic operations leads to memory corruption or unsafe state transitions.\nSuccessful exploitation of this flaw allows a local adversary, possessing baseline authorization, to manipulate system resources and execute arbitrary code with elevated privileges.\nThis introduces significant risk to the confidentiality, integrity, and availability of the host operating system, potentially enabling complete system compromise.\nPrerequisites for a successful attack include local access to the target system and the requisite authorization levels needed to interact with the vulnerable Windows DNS service or its supporting application programming interfaces.\nNo specific network exposure is strictly required if the attack vector is restricted to local inter-process communication channels or local administrative interfaces, emphasizing the danger of internal threat actors or secondary-stage malware execution following initial access.",
  "technicalDetails": "The root cause of the vulnerability stems from an integer overflow or wraparound condition within the Windows DNS component. When processing specially crafted inputs or size calculations, the affected code fails to adequately validate arithmetic operations against maximum boundary limits. Consequently, an integer calculation exceeding the maximum representable value wraps around to a small integer or zero.\nThis arithmetic discrepancy frequently misleads subsequent memory allocation routines, resulting in a buffer allocation that is significantly smaller than required to hold the incoming data. When the application subsequently attempts to copy or write data into this undersized buffer, a heap-based or stack-based buffer overflow occurs.\nThe attack flow proceeds as follows: First, the local attacker leverages their authorized access to interact with the vulnerable Windows DNS component. This interaction involves supplying a maliciously crafted payload, such as a specially structured DNS request, configuration parameter, or data stream that triggers the flawed arithmetic operation.\nSecond, the vulnerable function processes the input, initiating the vulnerable integer calculation. Because the input dictates the size parameters, the resulting integer wraparound causes a miscalculated memory allocation.\nThird, the routine writes data based on the original, larger size into the undersized buffer, corrupting adjacent memory structures, function pointers, or control flow data.\nFinally, the attacker hijacks the execution flow, redirecting it to malicious shellcode or leveraging the memory corruption to overwrite critical security descriptors or kernel objects, thereby elevating their execution context to high-privileged administrative or SYSTEM levels.\nThe affected component is the Windows DNS subsystem. Exploitation requires local access and authorization, operating primarily through local interfaces rather than network-exposed vectors, though the exact mechanics depend on local IPC mechanisms utilized by the service."
}