Description

Numeric truncation error in Windows DNS allows an authorized attacker to elevate privileges locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.7",
  "pubDate": "2026-08-11T17:18:59.743Z",
  "pubdate": "2026-08-11T17:18:59.743Z",
  "executiveSummary": "This vulnerability involves a numeric truncation error within Windows DNS, which can be exploited by an authorized threat actor to achieve local elevation of privileges. The flaw represents a critical security risk to host integrity, enabling lower-privileged local users to execute arbitrary code or commands with elevated privileges depending on the affected service context. Exploitation of this vulnerability requires the attacker to possess prior local access and authorization to interact with the target system, meaning remote exploitation without initial access or authentication is not facilitated by this vector alone. The root issue stems from improper handling and validation of numeric bounds during internal data processing within the DNS component, leading to memory corruption or unsafe state transitions. Successful exploitation compromises the confidentiality, integrity, and availability of the host operating system, potentially allowing the attacker to assume administrative control. Organizations utilizing vulnerable versions of Windows DNS are at risk of secondary attacks where an adversary leverages local footholds to escalate privileges and bypass security boundaries. Mitigation requires applying official vendor patches and hardening local access controls to minimize the attack surface against internal system components.",
  "technicalDetails": "The vulnerability is rooted in a numeric truncation error within the Windows DNS component, specifically occurring when integer values or buffer sizes are improperly cast, converted, or processed during internal operations. This flaw typically manifests when a larger data type is truncated to a smaller data type, leading to miscalculations in memory allocation, buffer sizing, or loop bounds. Consequently, these discrepancies can induce heap or stack-based buffer overflows, out-of-bounds memory reads and writes, or logic errors during the parsing of DNS-related data structures. The vulnerable component resides within the local Windows DNS service or associated application programming interfaces responsible for processing specific DNS queries, records, or internal administrative requests. To exploit this vulnerability, an authorized local attacker must interact with the vulnerable Windows DNS service or interface by supplying specially crafted inputs designed to trigger the numeric truncation condition. Because the attack vector relies on local access, the adversary must already possess a valid security context on the target machine, albeit with standard or low privileges. The attack flow proceeds as follows: first, the local attacker instantiates an interaction with the vulnerable Windows DNS component via local IPC mechanisms, command-line utilities, or API calls; second, the attacker transmits a meticulously crafted payload containing values engineered to induce numeric truncation upon processing; third, the truncation failure misleads the memory allocation routines, resulting in memory corruption or uncontrolled state manipulation; finally, the attacker leverages this manipulated execution state to inject and execute arbitrary code within the context of the elevated service or system process. Post-exploitation impact includes full local privilege escalation, allowing the execution of administrative commands, manipulation of system configurations, access to sensitive data stores, and potential persistence mechanisms established on the compromised host. Authentication is required to the extent that the attacker must have local logon capabilities and sufficient privileges to interact with the DNS service, while network exposure is strictly local as the vulnerability does not inherently provide remote vector access."
}